Linux "man" command can't vary width with groff 1.18

[Duncan Roe]

GROFF VERSION:
1.18

MACHINE:
i486-pc-linux-gnu

OS:
Linux 2.4.18

COMPILER:
gcc version 2.95.3 20010315 (release)

INPUT FILES:
#!/bin/sh
# This is a shell archive (produced by GNU sharutils 4.2.1).
# To extract the files from this archive, save it to some FILE, remove
# everything before the `!/bin/sh' line above, then type `sh FILE'.
#
# Made on 2002-11-23 17:09 EST by <address@hidden>.
# Source directory was `/work/home/duncanr/doc'.
#
# Existing files will *not* be overwritten unless `-c' is specified.
#
# This shar contains:
# length mode       name
# ------ ---------- ------------------------------------------
#    610 -rw-r--r-- t5zforce.txt
#
save_IFS="${IFS}"
IFS="${IFS}:"
gettext_dir=FAILED
locale_dir=FAILED
first_param="$1"
for dir in $PATH
do
  if test "$gettext_dir" = FAILED && test -f $dir/gettext \
     && ($dir/gettext --version >/dev/null 2>&1)
  then
    set `$dir/gettext --version 2>&1`
    if test "$3" = GNU
    then
      gettext_dir=$dir
    fi
  fi
  if test "$locale_dir" = FAILED && test -f $dir/shar \
     && ($dir/shar --print-text-domain-dir >/dev/null 2>&1)
  then
    locale_dir=`$dir/shar --print-text-domain-dir`
  fi
done
IFS="$save_IFS"
if test "$locale_dir" = FAILED || test "$gettext_dir" = FAILED
then
  echo=echo
else
  TEXTDOMAINDIR=$locale_dir
  export TEXTDOMAINDIR
  TEXTDOMAIN=sharutils
  export TEXTDOMAIN
  echo="$gettext_dir/gettext -s"
fi
if touch -am -t 200112312359.59 $$.touch >/dev/null 2>&1 && test ! -f 
200112312359.59 -a -f $$.touch; then
  shar_touch='touch -am -t $1$2$3$4$5$6.$7 "$8"'
elif touch -am 123123592001.59 $$.touch >/dev/null 2>&1 && test ! -f 
123123592001.59 -a ! -f 123123592001.5 -a -f $$.touch; then
  shar_touch='touch -am $3$4$5$6$1$2.$7 "$8"'
elif touch -am 1231235901 $$.touch >/dev/null 2>&1 && test ! -f 1231235901 -a 
-f $$.touch; then
  shar_touch='touch -am $3$4$5$6$2 "$8"'
else
  shar_touch=:
  echo
  $echo 'WARNING: not restoring timestamps.  Consider getting and'
  $echo "installing GNU \`touch', distributed in GNU File Utilities..."
  echo
fi
rm -f 200112312359.59 123123592001.59 123123592001.5 1231235901 $$.touch
#
if mkdir _sh29143; then
  $echo 'x -' 'creating lock directory'
else
  $echo 'failed to create lock directory'
  exit 1
fi
# ============= t5zforce.txt ==============
if test -f 't5zforce.txt' && test "$first_param" != -c; then
  $echo 'x -' SKIPPING 't5zforce.txt' '(file already exists)'
else
  $echo 'x -' extracting 't5zforce.txt' '(text)'
  sed 's/^X//' << 'SHAR_EOF' > 't5zforce.txt' &&
X.ll 8.5i
X.pl 1100i
X.TH ZFORCE 1
X.SH NAME
zforce \- force a '.gz' extension on all gzip files
X.SH SYNOPSIS
X.B zforce
[ name ...  ]
X.SH DESCRIPTION
X.I  zforce
forces a .gz extension on all
X.I gzip
files so that
X.I gzip
will not compress them twice.
This can be useful for files with names truncated after a file transfer.
On systems with a 14 char limitation on file names, the original name
is truncated to make room for the .gz suffix. For example,
12345678901234 is renamed to 12345678901.gz. A file name such as foo.tgz
is left intact.
X.SH "SEE ALSO"
gzip(1), znew(1), zmore(1), zgrep(1), zdiff(1), gzexe(1)
SHAR_EOF
  (set 20 02 11 23 16 38 59 't5zforce.txt'; eval "$shar_touch") &&
  chmod 0644 't5zforce.txt' ||
  $echo 'restore of' 't5zforce.txt' 'failed'
  if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \
  && ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then
    md5sum -c << SHAR_EOF >/dev/null 2>&1 \
    || $echo 't5zforce.txt:' 'MD5 check failed'
24d6e570deec6f63c0415875ee917234  t5zforce.txt
SHAR_EOF
  else
    shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 't5zforce.txt'`"
    test 610 -eq "$shar_count" ||
    $echo 't5zforce.txt:' 'original size' '610,' 'current size' "$shar_count!"
  fi
fi
rm -fr _sh29143
exit 0

COMMAND LINE:
cat t5zforce.txt|groff -mtty-char -Tascii -mandoc

DESCRIPTION OF INCORRECT BEHAVIOUR:
The file is printed with the same width regardless of the value of the ".ll"
directive on line 1.
This means the "man" command under Linux can't adjust the print width to suit
the size of your xterm window.
It works fine at 1.17.2.
Macros are all from groff.