commit: add --cleanup=scissors

Since 1a72cfd (commit -v: strip diffs and submodule shortlogs from the
commit message - 2013-12-05) we have a less fragile way to cut out
"git status" at the end of a commit message but it's only enabled for
stripping submodule shortlogs.

Add new cleanup option that reuses the same mechanism for the entire
"git status" without accidentally removing lines starting with '#'.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/builtin/commit.c b/builtin/commit.c
index 3767478..1033c50 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -113,6 +113,7 @@
 static enum {
 	CLEANUP_SPACE,
 	CLEANUP_NONE,
+	CLEANUP_SCISSORS,
 	CLEANUP_ALL
 } cleanup_mode;
 static const char *cleanup_arg;
@@ -754,7 +755,9 @@
 	strbuf_addstr(&committer_ident, git_committer_info(IDENT_STRICT));
 	if (use_editor && include_status) {
 		char *ai_tmp, *ci_tmp;
-		if (whence != FROM_COMMIT)
+		if (whence != FROM_COMMIT) {
+			if (cleanup_mode == CLEANUP_SCISSORS)
+				wt_status_add_cut_line(s->fp);
 			status_printf_ln(s, GIT_COLOR_NORMAL,
 			    whence == FROM_MERGE
 				? _("\n"
@@ -770,6 +773,7 @@
 				git_path(whence == FROM_MERGE
 					 ? "MERGE_HEAD"
 					 : "CHERRY_PICK_HEAD"));
+		}
 
 		fprintf(s->fp, "\n");
 		if (cleanup_mode == CLEANUP_ALL)
@@ -777,6 +781,8 @@
 				_("Please enter the commit message for your changes."
 				  " Lines starting\nwith '%c' will be ignored, and an empty"
 				  " message aborts the commit.\n"), comment_line_char);
+		else if (cleanup_mode == CLEANUP_SCISSORS && whence == FROM_COMMIT)
+			wt_status_add_cut_line(s->fp);
 		else /* CLEANUP_SPACE, that is. */
 			status_printf(s, GIT_COLOR_NORMAL,
 				_("Please enter the commit message for your changes."
@@ -1132,6 +1138,8 @@
 		cleanup_mode = CLEANUP_SPACE;
 	else if (!strcmp(cleanup_arg, "strip"))
 		cleanup_mode = CLEANUP_ALL;
+	else if (!strcmp(cleanup_arg, "scissors"))
+		cleanup_mode = use_editor ? CLEANUP_SCISSORS : CLEANUP_SPACE;
 	else
 		die(_("Invalid cleanup mode %s"), cleanup_arg);
 
@@ -1600,8 +1608,8 @@
 		die(_("could not read commit message: %s"), strerror(saved_errno));
 	}
 
-	/* Truncate the message just before the diff, if any. */
-	if (verbose)
+	if (verbose || /* Truncate the message just before the diff, if any. */
+	    cleanup_mode == CLEANUP_SCISSORS)
 		wt_status_truncate_message_at_cut_line(&sb);
 
 	if (cleanup_mode != CLEANUP_NONE)