[PATCH 2/2] ls-remote: pass heads/tags prefixes to transport

[Jeff King <peff@peff.net>]

Unlike its arbitrary text patterns, the --heads and --tags
options to ls-remote are true prefixes. We can pass this
information to the transport code. If the v2 protocol is in
use, that will reduce the size of the ref advertisement.

Note that the test added here succeeds both before and after
the patch. This is an optimization, not a bug-fix; it's just
making sure we didn't break anything.

Signed-off-by: Jeff King <peff@peff.net>
---
 builtin/ls-remote.c  | 5 +++++
 t/t5512-ls-remote.sh | 9 +++++++++
 2 files changed, 14 insertions(+)

diff --git a/builtin/ls-remote.c b/builtin/ls-remote.c
index 5faa8459d9..1d7f1f5ce2 100644
--- a/builtin/ls-remote.c
+++ b/builtin/ls-remote.c
@@ -92,6 +92,11 @@ int cmd_ls_remote(int argc, const char **argv, const char *prefix)
 		}
 	}
 
+	if (flags & REF_TAGS)
+		argv_array_push(&ref_prefixes, "refs/tags/");
+	if (flags & REF_HEADS)
+		argv_array_push(&ref_prefixes, "refs/heads/");
+
 	remote = remote_get(dest);
 	if (!remote) {
 		if (dest)
diff --git a/t/t5512-ls-remote.sh b/t/t5512-ls-remote.sh
index ca1b7e5bc1..91ee6841c1 100755
--- a/t/t5512-ls-remote.sh
+++ b/t/t5512-ls-remote.sh
@@ -311,4 +311,13 @@ test_expect_success 'ls-remote patterns work with all protocol versions' '
 	test_cmp expect actual.v2
 '
 
+test_expect_success 'ls-remote prefixes work with all protocol versions' '
+	git for-each-ref --format="%(objectname)	%(refname)" \
+		refs/heads/ refs/tags/ >expect &&
+	git -c protocol.version=1 ls-remote --heads --tags . >actual.v1 &&
+	test_cmp expect actual.v1 &&
+	git -c protocol.version=2 ls-remote --heads --tags . >actual.v2 &&
+	test_cmp expect actual.v2
+'
+
 test_done
-- 
2.19.1.1298.g19f18f2a22