t0001: handle diff --no-index gracefully

The test case 're-init to move gitdir symlink' wants to compare the
contents of `newdir/.git`, which is a symbolic link pointing to a file.
However, `git diff --no-index`, which is used by `test_cmp` on Windows,
does not resolve symlinks; It shows the symlink _target_ instead (with a
file mode of 120000). That is totally unexpected by the test case, which
as a consequence fails, meaning that it's a bug in the test case itself.

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

Author: dscho

t/t0001-init.sh

@@ -425,7 +425,11 @@ test_expect_success SYMLINKS 're-init to move gitdir symlink' '
 	git init --separate-git-dir ../realgitdir
 	) &&
 	echo "gitdir: $(pwd)/realgitdir" >expected &&
-	test_cmp expected newdir/.git &&
+	case "$GIT_TEST_CMP" in
+	# `git diff --no-index` does not resolve symlinks
+	*--no-index*) cmp expected newdir/.git;;
+	*) test_cmp expected newdir/.git;;
+	esac &&
 	test_cmp expected newdir/here &&
 	test_path_is_dir realgitdir/refs
 '