status: show "-v" diff even for initial commit

Since we can use the same "diff against empty tree" trick as
we do for the non-initial case, it is trivial to make this
work.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t7507-commit-verbose.sh

@@ -22,7 +22,7 @@ test_expect_success 'setup' '
 	git commit -F message
 '
 
-test_expect_failure 'initial commit shows verbose diff' '
+test_expect_success 'initial commit shows verbose diff' '
 	git commit --amend -v
 '
 

wt-status.c

@@ -279,7 +279,8 @@ static void wt_status_print_verbose(struct wt_status *s)
 	struct rev_info rev;
 
 	init_revisions(&rev, NULL);
-	setup_revisions(0, NULL, &rev, s->reference);
+	setup_revisions(0, NULL, &rev,
+		s->is_initial ? EMPTY_TREE_SHA1_HEX : s->reference);
 	rev.diffopt.output_format |= DIFF_FORMAT_PATCH;
 	rev.diffopt.detect_rename = 1;
 	rev.diffopt.file = s->fp;
@@ -343,7 +344,7 @@ void wt_status_print(struct wt_status *s)
 	else if (s->commitable)
 		 fprintf(s->fp, "# Untracked files not listed (use -u option to show untracked files)\n");
 
-	if (s->verbose && !s->is_initial)
+	if (s->verbose)
 		wt_status_print_verbose(s);
 	if (!s->commitable) {
 		if (s->amend)