Clone should use GIT_CHECKOUT_SAFE_CREATE

For clone to work as expected, it should be using a SAFE_CREATE
checkout (i.e. create files that are missing, even if the target
tree matches the current HEAD).

tests-clar/online/clone.c

@@ -91,7 +91,7 @@ void test_online_clone__can_checkout_a_cloned_repo(void)
 	bool checkout_progress_cb_was_called = false,
 		  fetch_progress_cb_was_called = false;
 
-	g_options.checkout_opts.checkout_strategy = GIT_CHECKOUT_SAFE;
+	g_options.checkout_opts.checkout_strategy = GIT_CHECKOUT_SAFE_CREATE;
 	g_options.checkout_opts.progress_cb = &checkout_progress;
 	g_options.checkout_opts.progress_payload = &checkout_progress_cb_was_called;
 	g_options.fetch_progress_cb = &fetch_progress;