Fix issue 563: error in _hg_commit in the contrib/zsh_completion script.

contrib/zsh_completion

@@ -380,7 +380,7 b' typeset -A _hg_cmd_globals'
   _arguments -s -w : $_hg_global_opts $_hg_pat_opts \
   '(--addremove -A)'{-A,--addremove}'[mark new/missing files as added/removed before committing]' \
   '(--message -m)'{-m+,--message}'[use <text> as commit message]:text:' \
-  '(--logfile -l)'{-l+,--logfile}'[read commit message from <file>]:log file:_file -g \*.txt' \
+  '(--logfile -l)'{-l+,--logfile}'[read commit message from <file>]:log file:_files -g \*.txt' \
   '(--date -d)'{-d+,--date}'[record datecode as commit date]:date code:' \
   '(--user -u)'{-u+,--user}'[record user as commiter]:user:' \
   '*:file:_hg_files'