git add -e: Explicitly specify that patch should have no color

After 4c7f181 (make color.ui default to 'auto', 2013-06-10), the
patch file to be edited during 'git add -e' receives all the color
codes.  This is because diffopt.use_color defaults to -1, which
causes want_color to now return 'auto'.

By explicitly setting use_color to 0, we can ensure the diff output
has no color codes in it.

Signed-off-by: Andrew Wong <andrew.kw.w@gmail.com>
Acked-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/add.c

@@ -238,6 +238,7 @@ static int edit_patch(int argc, const char **argv, const char *prefix)
 
 	argc = setup_revisions(argc, argv, &rev, NULL);
 	rev.diffopt.output_format = DIFF_FORMAT_PATCH;
+	rev.diffopt.use_color = 0;
 	DIFF_OPT_SET(&rev.diffopt, IGNORE_DIRTY_SUBMODULES);
 	out = open(file, O_CREAT | O_WRONLY, 0666);
 	if (out < 0)