Merge branch 'tb/commit-graph-object-dir'

The code to compute the commit-graph has been taught to use a more
robust way to tell if two object directories refer to the same
thing.

* tb/commit-graph-object-dir:
  commit-graph.h: use odb in 'load_commit_graph_one_fd_st'
  commit-graph.c: remove path normalization, comparison
  commit-graph.h: store object directory in 'struct commit_graph'
  commit-graph.h: store an odb in 'struct write_commit_graph_context'
  t5318: don't pass non-object directory to '--object-dir'

builtin/commit.c

@@ -1693,7 +1693,7 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
 		      "not exceeded, and then \"git restore --staged :/\" to recover."));
 
 	if (git_env_bool(GIT_TEST_COMMIT_GRAPH, 0) &&
-	    write_commit_graph_reachable(get_object_directory(), 0, NULL))
+	    write_commit_graph_reachable(the_repository->objects->odb, 0, NULL))
 		return 1;
 
 	repo_rerere(the_repository, 0);