[PATCH] diff: allow --color-moved with --no-ext-diff

["René Scharfe" <l.s.r@web.de>]

Since the option --color-moved was added by 2e2d5ac184 (diff.c: color
moved lines differently, 2017-06-30) we have been ignoring it if an
external diff program is configured, presumably because its overhead is
unnecessary in that case.

Do respect --color-moved if we don't actually use the configured
external diff, though.

Reported-by: lolligerhans@gmx.de
Signed-off-by: René Scharfe <l.s.r@web.de>
---
 diff.c                     | 3 ++-
 t/t4015-diff-whitespace.sh | 9 +++++++++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/diff.c b/diff.c
index 6e432cb8fc..aa0fb77761 100644
--- a/diff.c
+++ b/diff.c
@@ -4965,7 +4965,8 @@ void diff_setup_done(struct diff_options *options)
 	if (options->flags.follow_renames)
 		diff_check_follow_pathspec(&options->pathspec, 1);

-	if (!options->use_color || external_diff())
+	if (!options->use_color ||
+	    (options->flags.allow_external && external_diff()))
 		options->color_moved = 0;

 	if (options->filter_not) {
diff --git a/t/t4015-diff-whitespace.sh b/t/t4015-diff-whitespace.sh
index b443626afd..a1478680b6 100755
--- a/t/t4015-diff-whitespace.sh
+++ b/t/t4015-diff-whitespace.sh
@@ -1184,6 +1184,15 @@ test_expect_success 'detect moved code, complete file' '
 	test_cmp expected actual
 '

+test_expect_success '--color-moved with --no-ext-diff' '
+	test_config color.diff.oldMoved "normal red" &&
+	test_config color.diff.newMoved "normal green" &&
+	cp actual.raw expect &&
+	git -c diff.external=false diff HEAD --no-ext-diff \
+		--color-moved=zebra --color --no-renames >actual &&
+	test_cmp expect actual
+'
+
 test_expect_success 'detect malicious moved code, inside file' '
 	test_config color.diff.oldMoved "normal red" &&
 	test_config color.diff.newMoved "normal green" &&
--
2.45.2