t1092: prepare for changing protocol.file.allow

Explicitly cloning over the "file://" protocol in t1092 in preparation
for merging a security release which will change the default value of
this configuration to be "user".

Signed-off-by: Taylor Blau <me@ttaylorr.com>

Author: ttaylorr

t/t1092-sparse-checkout-compatibility.sh

@@ -390,6 +390,8 @@ test_expect_success 'submodule handling' '
 	test_all_match git add modules &&
 	test_all_match git commit -m "add modules directory" &&
 
+	test_config_global protocol.file.allow always &&
+
 	run_on_all git submodule add "$(pwd)/initial-repo" modules/sub &&
 	test_all_match git commit -m "add submodule" &&