repo-config: Fix late-night bug

This bug was hidden by the "future-proofing" of the test. Sigh.

When neither GIT_CONFIG nor GIT_CONFIG_LOCAL is set, do not use NULL,
but $GIT_DIR/config. Instead of using $GIT_DIR/config when only
GIT_CONFIG_LOCAL is set. Sorry.

Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Junio C Hamano <junkio@cox.net>

repo-config.c

@@ -74,8 +74,6 @@ static int get_value(const char* key_, const char* regex_)
 		const char *home = getenv("HOME");
 		local = getenv("GIT_CONFIG_LOCAL");
 		if (!local)
-			local = repo_config;
-		else
 			local = repo_config = strdup(git_path("config"));
 		if (home)
 			global = strdup(mkpath("%s/.gitconfig", home));