Merge branch 'ps/commit-graph-wo-globals'

Remove dependency on the_repository and other globals from the
commit-graph code, and other changes unrelated to de-globaling.

* ps/commit-graph-wo-globals:
  commit-graph: stop passing in redundant repository
  commit-graph: stop using `the_repository`
  commit-graph: stop using `the_hash_algo`
  commit-graph: refactor `parse_commit_graph()` to take a repository
  commit-graph: store the hash algorithm instead of its length
  commit-graph: stop using `the_hash_algo` via macros

builtin/merge.c

@@ -1863,7 +1863,7 @@ int cmd_merge(int argc,
 	if (squash) {
 		finish(head_commit, remoteheads, NULL, NULL);
 
-		git_test_write_commit_graph_or_die();
+		git_test_write_commit_graph_or_die(the_repository->objects->sources);
 	} else
 		write_merge_state(remoteheads);