[PATCH 09/10] merge.c: avoid duplicate unpack_trees_options_release() code

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

Refactor code added in 1c41d2805e4 (unpack_trees_options: free
messages when done, 2018-05-21) to use a ret/goto pattern, rather than
duplicating the end cleanup in the function.

This control flow will be matched in subsequent commits by various
other similar code, which often needs to do more than just call
unpack_trees_options_release(). Let's change this to consistently use
the same pattern everywhere.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 merge.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/merge.c b/merge.c
index 2f618425aff..2e3714ccaa0 100644
--- a/merge.c
+++ b/merge.c
@@ -54,6 +54,7 @@ int checkout_fast_forward(struct repository *r,
 	struct tree_desc t[MAX_UNPACK_TREES];
 	int i, nr_trees = 0;
 	struct lock_file lock_file = LOCK_INIT;
+	int ret = 0;
 
 	refresh_index(r->index, REFRESH_QUIET, NULL, NULL, NULL);
 
@@ -95,12 +96,14 @@ int checkout_fast_forward(struct repository *r,
 
 	if (unpack_trees(nr_trees, t, &opts)) {
 		rollback_lock_file(&lock_file);
-		unpack_trees_options_release(&opts);
-		return -1;
+		ret = -1;
+		goto cleanup;
 	}
-	unpack_trees_options_release(&opts);
 
 	if (write_locked_index(r->index, &lock_file, COMMIT_LOCK))
-		return error(_("unable to write new index file"));
-	return 0;
+		ret = error(_("unable to write new index file"));
+
+cleanup:
+	unpack_trees_options_release(&opts);
+	return ret;
 }
-- 
2.33.0.1404.g83021034c5d