blame_git: remove spuriuous goto

The recent addition of an error code to `pass_whole_blame` in ff8d2eb15
(blame_git: check return value of object lookup, 2017-03-20) introduced
a spurious goto. Remove it.
diff --git a/src/blame_git.c b/src/blame_git.c
index 735b62d..6d2f153 100644
--- a/src/blame_git.c
+++ b/src/blame_git.c
@@ -547,7 +547,6 @@
 		if (porigin->blob && origin->blob &&
 		    !git_oid_cmp(git_blob_id(porigin->blob), git_blob_id(origin->blob))) {
 			error = pass_whole_blame(blame, origin, porigin);
-				goto finish;
 			origin_decref(porigin);
 			goto finish;
 		}