Freeze with Emacs 21.1 and CVS Gnus

[Per Abrahamsen]

Using Emacs 21.1 and CVS Gnus, I get an uninteruptable infinite loop
whenever selecting an article from the summary buffer with a subject
that ends with a percent sign.

If I do it from X11, my X server become unresponsive, making it hard
to debug.  Running Gnus unser emacs -nw, I can get backtraces like
this:


(gdb) where
#0  0x80749eb in window_display_table (w=0x827e858) at window.c:1051
#1  0x805bab7 in init_iterator (it=0xbfffd298, w=0x827e858, charpos=1, 
    bytepos=1, row=0x0, base_face_id=DEFAULT_FACE_ID) at xdisp.c:1534
#2  0x806266d in resize_mini_window (w=0x827e858, exact_p=0) at xdisp.c:6582
#3  0x8062463 in display_echo_area_1 (a1=136833112, a2=405170404, a3=0, a4=0)
    at xdisp.c:6478
#4  0x806207f in with_echo_area_buffer (w=0x827e858, which=0, 
    fn=0x806244c <display_echo_area_1>, a1=136833112, a2=405170404, a3=0, a4=0)
    at xdisp.c:6271
#5  0x806241a in display_echo_area (w=0x827e858) at xdisp.c:6446
#6  0x8062fc7 in echo_area_display (update_frame_p=0) at xdisp.c:7024
#7  0x8065073 in redisplay_internal (preserve_echo_area=0) at xdisp.c:8482
#8  0x8064880 in redisplay () at xdisp.c:8231
#9  0x80cf3b5 in read_char (commandflag=1, nmaps=2, maps=0xbfffdb78, 
    prev_event=405170404, used_mouse_menu=0xbfffdbc0) at keyboard.c:2272
#10 0x80d5d65 in read_key_sequence (keybuf=0xbfffdcc8, bufsize=30, 
    prompt=405170404, dont_downcase_last=0, can_return_switch_frame=1, 
    fix_current_buffer=1) at keyboard.c:8180
#11 0x80cdf84 in command_loop_1 () at keyboard.c:1440
#12 0x811ec9f in internal_condition_case (bfun=0x80cdc90 <command_loop_1>, 
    handlers=405266724, hfun=0x80cd8d4 <cmd_error>) at eval.c:1267
#13 0x80cdb68 in command_loop_2 () at keyboard.c:1245
#14 0x811e82f in internal_catch (tag=405288804, 
    func=0x80cdb44 <command_loop_2>, arg=405170404) at eval.c:1030
#15 0x80cdad5 in command_loop () at keyboard.c:1216
#16 0x80cd691 in recursive_edit_1 () at keyboard.c:950
#17 0x80cd7c0 in Frecursive_edit () at keyboard.c:1006
#18 0x812070c in Ffuncall (nargs=1, args=0xbfffe008) at eval.c:2652
#19 0x8146a7c in Fbyte_code (bytestr=953589980, vector=1221744152, maxdepth=3)
    at bytecode.c:716
#20 0x811fd65 in Feval (form=1490404956) at eval.c:2019
#21 0x811db53 in Fprogn (args=1490404748) at eval.c:431
#22 0x807a5fb in Fsave_window_excursion (args=1490404748) at window.c:5331
#23 0x8146e84 in Fbyte_code (bytestr=953590060, vector=1221883656, maxdepth=25)
    at bytecode.c:865
#24 0x8120cd7 in funcall_lambda (fun=1221744400, nargs=2, 
    arg_vector=0xbfffe30c) at eval.c:2847
#25 0x8120841 in Ffuncall (nargs=3, args=0xbfffe308) at eval.c:2712
#26 0x8120137 in Fapply (nargs=2, args=0xbfffe388) at eval.c:2169
#27 0x8120431 in apply1 (fn=405533804, arg=1490401180) at eval.c:2419
#28 0x811d8d7 in call_debugger (arg=1490401180) at eval.c:264
#29 0x811f395 in find_handler_clause (handlers=405266724, 
    conditions=1478952644, sig=405266796, data=1490401204, 
    debugger_value_ptr=0xbfffe46c) at eval.c:1607
#30 0x811f016 in Fsignal (error_symbol=405266796, data=1490401204)
    at eval.c:1430
#31 0x81105aa in args_out_of_range (a1=51, a2=51) at data.c:137
#32 0x8155bb3 in validate_interval_range (object=953702444, begin=0xbfffe528, 
    end=0xbfffe528, force=0) at textprop.c:164
#33 0x8156462 in Ftext_properties_at (position=51, object=953702444)
    at textprop.c:549
#34 0x81564ca in Fget_text_property (position=51, prop=405170764, 
    object=953702444) at textprop.c:570
#35 0x809ed14 in face_at_string_position (w=0x8da3e20, string=953702444, 
    pos=51, bufpos=0, region_beg=-1, region_end=-1, endptr=0xbfffe668, 
    base_face_id=MODE_LINE_FACE_ID, mouse_p=0) at xfaces.c:6887
#36 0x806e31a in display_string (string=0x8161d05 "%", lisp_string=405170404, 
    face_string=953702444, face_string_pos=51, start=0, it=0xbfffe824, 
    field_width=0, precision=-59, max_x=0, multibyte=0) at xdisp.c:14372
#37 0x806d40d in display_mode_element (it=0xbfffe824, depth=4, 
    field_width=-12, precision=-12, elt=953702444) at xdisp.c:13539
#38 0x806d6ce in display_mode_element (it=0xbfffe824, depth=3, 
    field_width=-12, precision=-12, elt=1490400076) at xdisp.c:13689
#39 0x806d6ce in display_mode_element (it=0xbfffe824, depth=1, field_width=0, 
    precision=0, elt=1490697276) at xdisp.c:13689
#40 0x806d130 in display_mode_line (w=0x8da3e20, face_id=MODE_LINE_FACE_ID, 
    format=1490697308) at xdisp.c:13402
#41 0x806d031 in display_mode_lines (w=0x8da3e20) at xdisp.c:13359
#42 0x8068a45 in redisplay_window (window=1222262304, just_this_one_p=0)
    at xdisp.c:10422
#43 0x8066091 in redisplay_windows (window=1210574624) at xdisp.c:9182
#44 0x8066084 in redisplay_windows (window=1222261992) at xdisp.c:9180
#45 0x8065843 in redisplay_internal (preserve_echo_area=0) at xdisp.c:8786
#46 0x8064880 in redisplay () at xdisp.c:8231
#47 0x80cf3b5 in read_char (commandflag=1, nmaps=2, maps=0xbffff3e4, 
    prev_event=405170404, used_mouse_menu=0xbffff42c) at keyboard.c:2272
#48 0x80d5d65 in read_key_sequence (keybuf=0xbffff534, bufsize=30, 
    prompt=405170404, dont_downcase_last=0, can_return_switch_frame=1, 
    fix_current_buffer=1) at keyboard.c:8180
#49 0x80cdf84 in command_loop_1 () at keyboard.c:1440
#50 0x811ec9f in internal_condition_case (bfun=0x80cdc90 <command_loop_1>, 
    handlers=405266724, hfun=0x80cd8d4 <cmd_error>) at eval.c:1267
#51 0x80cdb68 in command_loop_2 () at keyboard.c:1245
#52 0x811e82f in internal_catch (tag=405228332, 
    func=0x80cdb44 <command_loop_2>, arg=405170404) at eval.c:1030
#53 0x80cdb17 in command_loop () at keyboard.c:1224
#54 0x80cd691 in recursive_edit_1 () at keyboard.c:950
#55 0x80cd7c0 in Frecursive_edit () at keyboard.c:1006
#56 0x80cc739 in main (argc=2, argv=0xbffffaf4, envp=0xbffffb00)
    at emacs.c:1547

If I let it continue and interrupt, I get a different backtrace:

(gdb) cont
Continuing.
Program received signal SIGINT, Interrupt.
0x809457d in append_glyph (it=0xbfffcfe8) at term.c:1806
1806    {
(gdb) where
#0  0x809457d in append_glyph (it=0xbfffcfe8) at term.c:1806
#1  0x806becc in extend_face_to_end_of_line (it=0xbfffcfe8) at xdisp.c:12635
#2  0x806c866 in display_line (it=0xbfffcfe8) at xdisp.c:13029
#3  0x8068eb9 in try_window (window=1222262304, pos={charpos = 1, bytepos = 1})
    at xdisp.c:10562
#4  0x8068352 in redisplay_window (window=1222262304, just_this_one_p=0)
    at xdisp.c:10230
#5  0x8066091 in redisplay_windows (window=1210574624) at xdisp.c:9182
#6  0x8066084 in redisplay_windows (window=1222261992) at xdisp.c:9180
#7  0x8065843 in redisplay_internal (preserve_echo_area=0) at xdisp.c:8786
#8  0x8064880 in redisplay () at xdisp.c:8231
#9  0x80cf3b5 in read_char (commandflag=1, nmaps=2, maps=0xbfffdb78, 
    prev_event=405170404, used_mouse_menu=0xbfffdbc0) at keyboard.c:2272
#10 0x80d5d65 in read_key_sequence (keybuf=0xbfffdcc8, bufsize=30, 
    prompt=405170404, dont_downcase_last=0, can_return_switch_frame=1, 
    fix_current_buffer=1) at keyboard.c:8180
#11 0x80cdf84 in command_loop_1 () at keyboard.c:1440
#12 0x811ec9f in internal_condition_case (bfun=0x80cdc90 <command_loop_1>, 
    handlers=405266724, hfun=0x80cd8d4 <cmd_error>) at eval.c:1267
#13 0x80cdb68 in command_loop_2 () at keyboard.c:1245
#14 0x811e82f in internal_catch (tag=405288804, 
    func=0x80cdb44 <command_loop_2>, arg=405170404) at eval.c:1030
#15 0x80cdad5 in command_loop () at keyboard.c:1216
#16 0x80cd691 in recursive_edit_1 () at keyboard.c:950
#17 0x80cd7c0 in Frecursive_edit () at keyboard.c:1006
#18 0x812070c in Ffuncall (nargs=1, args=0xbfffe008) at eval.c:2652
#19 0x8146a7c in Fbyte_code (bytestr=953589980, vector=1221744152, maxdepth=3)
    at bytecode.c:716
#20 0x811fd65 in Feval (form=1490404956) at eval.c:2019
#21 0x811db53 in Fprogn (args=1490404748) at eval.c:431
#22 0x807a5fb in Fsave_window_excursion (args=1490404748) at window.c:5331
#23 0x8146e84 in Fbyte_code (bytestr=953590060, vector=1221883656, maxdepth=25)
    at bytecode.c:865
#24 0x8120cd7 in funcall_lambda (fun=1221744400, nargs=2, 
    arg_vector=0xbfffe30c) at eval.c:2847
#25 0x8120841 in Ffuncall (nargs=3, args=0xbfffe308) at eval.c:2712
#26 0x8120137 in Fapply (nargs=2, args=0xbfffe388) at eval.c:2169
#27 0x8120431 in apply1 (fn=405533804, arg=1490401180) at eval.c:2419
#28 0x811d8d7 in call_debugger (arg=1490401180) at eval.c:264
#29 0x811f395 in find_handler_clause (handlers=405266724, 
    conditions=1478952644, sig=405266796, data=1490401204, 
    debugger_value_ptr=0xbfffe46c) at eval.c:1607
#30 0x811f016 in Fsignal (error_symbol=405266796, data=1490401204)
    at eval.c:1430
#31 0x81105aa in args_out_of_range (a1=51, a2=51) at data.c:137
#32 0x8155bb3 in validate_interval_range (object=953702444, begin=0xbfffe528, 
    end=0xbfffe528, force=0) at textprop.c:164
#33 0x8156462 in Ftext_properties_at (position=51, object=953702444)
    at textprop.c:549
#34 0x81564ca in Fget_text_property (position=51, prop=405170764, 
    object=953702444) at textprop.c:570
#35 0x809ed14 in face_at_string_position (w=0x8da3e20, string=953702444, 
    pos=51, bufpos=0, region_beg=-1, region_end=-1, endptr=0xbfffe668, 
    base_face_id=MODE_LINE_FACE_ID, mouse_p=0) at xfaces.c:6887
#36 0x806e31a in display_string (string=0x8161d05 "%", lisp_string=405170404, 
    face_string=953702444, face_string_pos=51, start=0, it=0xbfffe824, 
    field_width=0, precision=-59, max_x=0, multibyte=0) at xdisp.c:14372
#37 0x806d40d in display_mode_element (it=0xbfffe824, depth=4, 
    field_width=-12, precision=-12, elt=953702444) at xdisp.c:13539
#38 0x806d6ce in display_mode_element (it=0xbfffe824, depth=3, 
    field_width=-12, precision=-12, elt=1490400076) at xdisp.c:13689
#39 0x806d6ce in display_mode_element (it=0xbfffe824, depth=1, field_width=0, 
    precision=0, elt=1490697276) at xdisp.c:13689
#40 0x806d130 in display_mode_line (w=0x8da3e20, face_id=MODE_LINE_FACE_ID, 
    format=1490697308) at xdisp.c:13402
#41 0x806d031 in display_mode_lines (w=0x8da3e20) at xdisp.c:13359
#42 0x8068a45 in redisplay_window (window=1222262304, just_this_one_p=0)
    at xdisp.c:10422
#43 0x8066091 in redisplay_windows (window=1210574624) at xdisp.c:9182
#44 0x8066084 in redisplay_windows (window=1222261992) at xdisp.c:9180
#45 0x8065843 in redisplay_internal (preserve_echo_area=0) at xdisp.c:8786
#46 0x8064880 in redisplay () at xdisp.c:8231
#47 0x80cf3b5 in read_char (commandflag=1, nmaps=2, maps=0xbffff3e4, 
    prev_event=405170404, used_mouse_menu=0xbffff42c) at keyboard.c:2272
#48 0x80d5d65 in read_key_sequence (keybuf=0xbffff534, bufsize=30, 
    prompt=405170404, dont_downcase_last=0, can_return_switch_frame=1, 
    fix_current_buffer=1) at keyboard.c:8180
#49 0x80cdf84 in command_loop_1 () at keyboard.c:1440
#50 0x811ec9f in internal_condition_case (bfun=0x80cdc90 <command_loop_1>, 
    handlers=405266724, hfun=0x80cd8d4 <cmd_error>) at eval.c:1267
#51 0x80cdb68 in command_loop_2 () at keyboard.c:1245
#52 0x811e82f in internal_catch (tag=405228332, 
    func=0x80cdb44 <command_loop_2>, arg=405170404) at eval.c:1030
#53 0x80cdb17 in command_loop () at keyboard.c:1224
#54 0x80cd691 in recursive_edit_1 () at keyboard.c:950
#55 0x80cd7c0 in Frecursive_edit () at keyboard.c:1006
#56 0x80cc739 in main (argc=2, argv=0xbffffaf4, envp=0xbffffb00)
    at emacs.c:1547