setup_discovered_git_dir(): plug memory leak

The setup_explicit_git_dir() function does not take custody of the string
passed as first parameter; we have to release it if we turned the value of
git_dir into an absolute path.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

setup.c

@@ -703,11 +703,16 @@ static const char *setup_discovered_git_dir(const char *gitdir,
 
 	/* --work-tree is set without --git-dir; use discovered one */
 	if (getenv(GIT_WORK_TREE_ENVIRONMENT) || git_work_tree_cfg) {
+		char *to_free = NULL;
+		const char *ret;
+
 		if (offset != cwd->len && !is_absolute_path(gitdir))
-			gitdir = real_pathdup(gitdir, 1);
+			gitdir = to_free = real_pathdup(gitdir, 1);
 		if (chdir(cwd->buf))
 			die_errno("Could not come back to cwd");
-		return setup_explicit_git_dir(gitdir, cwd, nongit_ok);
+		ret = setup_explicit_git_dir(gitdir, cwd, nongit_ok);
+		free(to_free);
+		return ret;
 	}
 
 	/* #16.2, #17.2, #20.2, #21.2, #24, #25, #28, #29 (see t1510) */