Revert "git-gui: remove lines starting with the comment character"

This reverts commit b9a4386.

This commit causes breakage on macOS (10.13). It causes errors on
startup and completely breaks the commit functionality. There are two
main problems. First, it uses `string cat` which is not supported on
older Tcl versions. Second, it does a half close of the bidirectional
pipe to git-stripspace which is also not supported on older Tcl
versions.

Reported-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Pratyush Yadav <me@yadavpratyush.com>

Author: prati0100

git-gui.sh

@@ -875,7 +875,6 @@ set default_config(merge.summary) false
 set default_config(merge.verbosity) 2
 set default_config(user.name) {}
 set default_config(user.email) {}
-set default_config(core.commentchar) "#"
 
 set default_config(gui.encoding) [encoding system]
 set default_config(gui.matchtrackingbranch) false
@@ -3437,10 +3436,6 @@ proc trace_commit_type {varname args} {
 	merge         {set txt [mc "Merge Commit Message:"]}
 	*             {set txt [mc "Commit Message:"]}
 	}
-
-	set comment_char [get_config core.commentchar]
-	set txt [string cat $txt \
-				 [mc " (Lines starting with '$comment_char' will be ignored)"]]
 	$ui_coml conf -text $txt
 }
 trace add variable commit_type write trace_commit_type

lib/commit.tcl

@@ -141,20 +141,6 @@ proc setup_commit_encoding {msg_wt {quiet 0}} {
 	}
 }
 
-proc strip_msg {msg} {
-	set cmd [concat [list | ] [_git_cmd stripspace] --strip-comments]
-	_trace_exec $cmd
-	set fd [open $cmd r+]
-	fconfigure $fd -translation binary -encoding utf-8
-
-	puts -nonewline $fd $msg
-	close $fd w
-	set result [read $fd]
-	close $fd
-
-	return $result
-}
-
 proc commit_tree {} {
 	global HEAD commit_type file_states ui_comm repo_config
 	global pch_error
@@ -221,8 +207,8 @@ You must stage at least 1 file before you can commit.
 
 	# -- A message is required.
 	#
-	set msg [strip_msg [$ui_comm get 1.0 end]]
-
+	set msg [string trim [$ui_comm get 1.0 end]]
+	regsub -all -line {[ \t\r]+$} $msg {} msg
 	if {$msg eq {}} {
 		error_popup [mc "Please supply a commit message.