config.c: don't leak memory in handle_path_include()

Fix a memory leak in the error() path in handle_path_include(), this
allows us to run t1305-config-include.sh under SANITIZE=leak,
previously 4 tests there would fail. This fixes up a leak in
9b25a0b52e (config: add include directive, 2012-02-06).

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

config.c

@@ -148,8 +148,10 @@ static int handle_path_include(const char *path, struct config_include_data *inc
 	if (!is_absolute_path(path)) {
 		char *slash;
 
-		if (!cf || !cf->path)
-			return error(_("relative config includes must come from files"));
+		if (!cf || !cf->path) {
+			ret = error(_("relative config includes must come from files"));
+			goto cleanup;
+		}
 
 		slash = find_last_dir_sep(cf->path);
 		if (slash)
@@ -167,6 +169,7 @@ static int handle_path_include(const char *path, struct config_include_data *inc
 		ret = git_config_from_file(git_config_include, path, inc);
 		inc->depth--;
 	}
+cleanup:
 	strbuf_release(&buf);
 	free(expanded);
 	return ret;

t/t1305-config-include.sh

@@ -1,6 +1,7 @@
 #!/bin/sh
 
 test_description='test config file include directives'
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 # Force setup_explicit_git_dir() to run until the end. This is needed