remote: fix leaking peer ref when expanding refmap

When expanding remote refs via the refspec in `get_expanded_map()`, we
first copy the remote ref and then override its peer ref with the
expanded name. This may cause a memory leak though in case the peer ref
is already set, as this field is being copied by `copy_ref()`, as well.

Fix the leak by freeing the peer ref before we re-assign the field.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: pks-t

remote.c

@@ -2081,6 +2081,8 @@ static struct ref *get_expanded_map(const struct ref *remote_refs,
 		    !ignore_symref_update(expn_name, &scratch)) {
 			struct ref *cpy = copy_ref(ref);
 
+			if (cpy->peer_ref)
+				free_one_ref(cpy->peer_ref);
 			cpy->peer_ref = alloc_ref(expn_name);
 			if (refspec->force)
 				cpy->peer_ref->force = 1;

t/t5536-fetch-conflicts.sh

@@ -2,6 +2,7 @@
 
 test_description='fetch handles conflicting refspecs correctly'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 D=$(pwd)

t/t5553-set-upstream.sh

@@ -4,6 +4,7 @@ test_description='"git fetch/pull --set-upstream" basic tests.'
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 check_config () {

t/t5703-upload-pack-ref-in-want.sh

@@ -2,6 +2,7 @@
 
 test_description='upload-pack ref-in-want'
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 get_actual_refs () {

t/t6050-replace.sh

@@ -7,6 +7,7 @@ test_description='Tests replace refs functionality'
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 . "$TEST_DIRECTORY/lib-gpg.sh"