[PATCH 5/5] lock_ref_for_update(): avoid a symref resolution

[Michael Haggerty <mhagger@alum.mit.edu>]

If we're overwriting a symref with a SHA-1, we need to resolve the value
of the symref (1) to check against update->old_sha1 and (2) to write to
its reflog. However, we've already read the symref itself and know its
referent. So there is no need to read the symref's value through the
symref; we can read the referent directly.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
---
 refs/files-backend.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/refs/files-backend.c b/refs/files-backend.c
index 98c8b95..b8d7a9a 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -3481,7 +3481,7 @@ static int lock_ref_for_update(struct ref_update *update,
 			 * the transaction, so we have to read it here
 			 * to record and possibly check old_sha1:
 			 */
-			if (read_ref_full(update->refname, 0,
+			if (read_ref_full(referent.buf, 0,
 					  lock->old_oid.hash, NULL)) {
 				if (update->flags & REF_HAVE_OLD) {
 					strbuf_addf(err, "cannot lock ref '%s': "
-- 
2.8.1