Merge branch 'rs/diff-quiet-no-rename'

As "git diff --quiet" only cares about the existence of any
changes, disable rename/copy detection to skip more expensive
processing whose result will be discarded anyway.

* rs/diff-quiet-no-rename:
  diff: disable rename detection with --quiet

Author: gitster

diff.c

@@ -4987,6 +4987,8 @@ void diff_setup_done(struct diff_options *options)
 	if (options->flags.quick) {
 		options->output_format = DIFF_FORMAT_NO_OUTPUT;
 		options->flags.exit_with_status = 1;
+		options->detect_rename = 0;
+		options->flags.find_copies_harder = 0;
 	}
 
 	/*

t/t4007-rename-3.sh

@@ -41,6 +41,16 @@ test_expect_success 'copy detection, cached' '
 	compare_diff_raw current expected
 '
 
+test_expect_success 'exit code of quiet copy detection' '
+	test_expect_code 1 \
+	git diff --quiet --cached --find-copies-harder $tree
+'
+
+test_expect_success 'exit code of quiet copy detection with --no-ext-diff' '
+	test_expect_code 1 \
+	git diff --quiet --cached --find-copies-harder --no-ext-diff $tree
+'
+
 # In the tree, there is only path0/COPYING.  In the cache, path0 and
 # path1 both have COPYING and the latter is a copy of path0/COPYING.
 # However when we say we care only about path1, we should just see