fixup??? Introduce helper to create symlinks that knows about index_state

Ah, `git rerere` works well, when it works. But sometimes, one makes
a mistake, and cannot figure out which recorded resolution to forget,
and does not want to blow them all away. Oh well.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

setup.c

@@ -2396,7 +2396,6 @@ static int create_default_files(const char *template_path,
 		repo_git_path_replace(the_repository, &path, "tXXXXXX");
 		if (!close(xmkstemp(path.buf)) &&
 		    !unlink(path.buf) &&
-		    !symlink("testing", path.buf) &&
 		    !create_symlink(NULL, "testing", path.buf) &&
 		    !lstat(path.buf, &st1) &&
 		    S_ISLNK(st1.st_mode))