From: Junio C Hamano <gitster@pobox.com>
Date: Tue, 10 Mar 2015 20:52:39 +0000 (-0700)
Subject: Merge branch 'mh/expire-updateref-fixes'
X-Git-Tag: v2.4.0-rc0~51
X-Git-Url: https://git.lorimer.id.au/gitweb.git/diff_plain/82b7e651990dce7016a903cb020e3dc0eba2ecfe

Merge branch 'mh/expire-updateref-fixes'

Various issues around "reflog expire", e.g. using --updateref when
expiring a reflog for a symbolic reference, have been corrected
and/or made saner.

* mh/expire-updateref-fixes:
reflog_expire(): never update a reference to null_sha1
reflog_expire(): ignore --updateref for symbolic references
reflog: improve and update documentation
struct ref_lock: delete the force_write member
lock_ref_sha1_basic(): do not set force_write for missing references
write_ref_sha1(): move write elision test to callers
write_ref_sha1(): remove check for lock == NULL
---

82b7e651990dce7016a903cb020e3dc0eba2ecfe
diff --cc refs.c
index 8d46b08055,05a4be0c06..e23542b386
--- a/refs.c
+++ b/refs.c
@@@ -3848,11 -3783,21 +3832,22 @@@ int ref_transaction_commit(struct ref_t
  	/* Perform updates first so live commits remain referenced */
  	for (i = 0; i < n; i++) {
  		struct ref_update *update = updates[i];
 +		int flags = update->flags;
  
 -		if (!is_null_sha1(update->new_sha1)) {
 +		if ((flags & REF_HAVE_NEW) && !is_null_sha1(update->new_sha1)) {
- 			if (write_ref_sha1(update->lock, update->new_sha1,
- 					   update->msg)) {
+ 			int overwriting_symref = ((update->type & REF_ISSYMREF) &&
+ 						  (update->flags & REF_NODEREF));
+ 
+ 			if (!overwriting_symref
+ 			    && !hashcmp(update->lock->old_sha1, update->new_sha1)) {
+ 				/*
+ 				 * The reference already has the desired
+ 				 * value, so we don't need to write it.
+ 				 */
+ 				unlock_ref(update->lock);
+ 				update->lock = NULL;
+ 			} else if (write_ref_sha1(update->lock, update->new_sha1,
+ 						  update->msg)) {
  				update->lock = NULL; /* freed by write_ref_sha1 */
  				strbuf_addf(err, "Cannot update the ref '%s'.",
  					    update->refname);