init: show "Reinit" message even in an (existing) empty repository

Earlier, git-init tested for a valid HEAD ref, but if the repository
was empty, there was none.  Instead, test for the existence of
the file $GIT_DIR/HEAD.

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

builtin-init-db.c

@@ -167,9 +167,9 @@ static int create_default_files(const char *git_dir, const char *template_path)
 {
 	unsigned len = strlen(git_dir);
 	static char path[PATH_MAX];
-	unsigned char sha1[20];
 	struct stat st1;
 	char repo_version_string[10];
+	char junk[2];
 	int reinit;
 	int filemode;
 
@@ -219,7 +219,8 @@ static int create_default_files(const char *git_dir, const char *template_path)
 	 * branch, if it does not exist yet.
 	 */
 	strcpy(path + len, "HEAD");
-	reinit = !read_ref("HEAD", sha1);
+	reinit = (!access(path, R_OK)
+		  || readlink(path, junk, sizeof(junk)-1) != -1);
 	if (!reinit) {
 		if (create_symref("HEAD", "refs/heads/master", NULL) < 0)
 			exit(1);

t/t0001-init.sh

@@ -113,4 +113,21 @@ test_expect_success 'GIT_DIR & GIT_WORK_TREE (2)' '
 	fi
 '
 
+test_expect_success 'reinit' '
+
+	(
+		unset GIT_CONFIG GIT_WORK_TREE GIT_CONFIG
+
+		mkdir again &&
+		cd again &&
+		git init >out1 2>err1 &&
+		git init >out2 2>err2
+	) &&
+	grep "Initialized empty" again/out1 &&
+	grep "Reinitialized existing" again/out2 &&
+	>again/empty &&
+	test_cmp again/empty again/err1 &&
+	test_cmp again/empty again/err2
+'
+
 test_done