Merge branch 'jk/rev-list-count-with-bitmap' into next

"git rev-list --count" whose walk-length is limited with "-n"
option did not work well with the counting optimized to look at the
bitmap index.

* jk/rev-list-count-with-bitmap:
  rev-list: disable bitmaps when "-n" is used with listing objects
  rev-list: "adjust" results of "--count --use-bitmap-index -n"

Author: gitster

builtin/rev-list.c

@@ -358,12 +358,16 @@ int cmd_rev_list(int argc, const char **argv, const char *prefix)
 	if (use_bitmap_index && !revs.prune) {
 		if (revs.count && !revs.left_right && !revs.cherry_mark) {
 			uint32_t commit_count;
+			int max_count = revs.max_count;
 			if (!prepare_bitmap_walk(&revs)) {
 				count_bitmap_commit_list(&commit_count, NULL, NULL, NULL);
+				if (max_count >= 0 && max_count < commit_count)
+					commit_count = max_count;
 				printf("%d\n", commit_count);
 				return 0;
 			}
-		} else if (revs.tag_objects && revs.tree_objects && revs.blob_objects) {
+		} else if (revs.max_count < 0 &&
+			   revs.tag_objects && revs.tree_objects && revs.blob_objects) {
 			if (!prepare_bitmap_walk(&revs)) {
 				traverse_bitmap_commit_list(&show_object_fast);
 				return 0;

t/t5310-pack-bitmaps.sh

@@ -47,6 +47,12 @@ rev_list_tests() {
 		test_cmp expect actual
 	'
 
+	test_expect_success "counting commits with limit ($state)" '
+		git rev-list --count -n 1 HEAD >expect &&
+		git rev-list --use-bitmap-index --count -n 1 HEAD >actual &&
+		test_cmp expect actual
+	'
+
 	test_expect_success "counting non-linear history ($state)" '
 		git rev-list --count other...master >expect &&
 		git rev-list --use-bitmap-index --count other...master >actual &&