bug#40250: 26.3; gdb-mode incorrectly handles gdb's `explore' command

[Eli Zaretskii]

> From: Vladimir Nikishkin <lockywolf@gmail.com>
> Date: Fri, 27 Mar 2020 15:25:05 +0800
> 
> 2) run M-x gdb RET RET
> 3)break 14
> (should put a breakpoint at the print statement)
> 4)run RET
> 5)explore a
> (a is the specially prepared data object)
> gdb should ask you for a choice
> 6)0
> (the only choice)
> 
> Expected result: display of the contents of a
> Obtained result: silent return to the (gdb) prompt

Thanks.  Does the change below fix this?

diff --git a/lisp/progmodes/gdb-mi.el b/lisp/progmodes/gdb-mi.el
index 7fb3687..e046264 100644
--- a/lisp/progmodes/gdb-mi.el
+++ b/lisp/progmodes/gdb-mi.el
@@ -1849,7 +1849,7 @@ gdb-control-commands-regexp
    "comm\\(a\\(n\\(ds?\\)?\\)?\\)?\\|if\\|while"
    "\\|def\\(i\\(ne?\\)?\\)?\\|doc\\(u\\(m\\(e\\(nt?\\)?\\)?\\)?\\)?\\|"
    gdb-python-guile-commands-regexp
-   "\\|while-stepping\\|stepp\\(i\\(ng?\\)?\\)?\\|ws\\|actions"
+   "\\|while-stepping\\|stepp\\(i\\(ng?\\)?\\)?\\|ws\\|actions\\|explore"
    "\\)\\([[:blank:]]+\\([^[:blank:]]*\\)\\)?$")
   "Regexp matching GDB commands that enter a recursive reading loop.
 As long as GDB is in the recursive reading loop, it does not expect