submodule--helper: use submodule_from_path in set-{url,branch}

The commands need a path to a submodule but treated it as the name when
modifying the .gitmodules file, leading to confusion when a submodule's
name does not match its path.

Because calling submodule_from_path initializes the submodule cache, we
need to manually trigger a reread before syncing, as the cache is
missing the config change we just made.

Signed-off-by: Jan Alexander Steffens (heftig) <heftig@archlinux.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/submodule--helper.c

@@ -2901,19 +2901,26 @@ static int module_set_url(int argc, const char **argv, const char *prefix)
 		N_("git submodule set-url [--quiet] <path> <newurl>"),
 		NULL
 	};
+	const struct submodule *sub;
 
 	argc = parse_options(argc, argv, prefix, options, usage, 0);
 
 	if (argc != 2 || !(path = argv[0]) || !(newurl = argv[1]))
 		usage_with_options(usage, options);
 
-	config_name = xstrfmt("submodule.%s.url", path);
+	sub = submodule_from_path(the_repository, null_oid(), path);
 
+	if (!sub)
+		die(_("no submodule mapping found in .gitmodules for path '%s'"),
+		    path);
+
+	config_name = xstrfmt("submodule.%s.url", sub->name);
 	config_set_in_gitmodules_file_gently(config_name, newurl);
-	sync_submodule(path, prefix, NULL, quiet ? OPT_QUIET : 0);
 
-	free(config_name);
+	repo_read_gitmodules (the_repository, 0);
+	sync_submodule(sub->path, prefix, NULL, quiet ? OPT_QUIET : 0);
 
+	free(config_name);
 	return 0;
 }
 
@@ -2941,6 +2948,7 @@ static int module_set_branch(int argc, const char **argv, const char *prefix)
 		N_("git submodule set-branch [-q|--quiet] (-b|--branch) <branch> <path>"),
 		NULL
 	};
+	const struct submodule *sub;
 
 	argc = parse_options(argc, argv, prefix, options, usage, 0);
 
@@ -2953,7 +2961,13 @@ static int module_set_branch(int argc, const char **argv, const char *prefix)
 	if (argc != 1 || !(path = argv[0]))
 		usage_with_options(usage, options);
 
-	config_name = xstrfmt("submodule.%s.branch", path);
+	sub = submodule_from_path(the_repository, null_oid(), path);
+
+	if (!sub)
+		die(_("no submodule mapping found in .gitmodules for path '%s'"),
+		    path);
+
+	config_name = xstrfmt("submodule.%s.branch", sub->name);
 	ret = config_set_in_gitmodules_file_gently(config_name, opt_branch);
 
 	free(config_name);