As already commented by @JohannesTyra at 3f0adca#commitcomment-149925742 the change to include test/ in .gitattributes not only messes with the autoloader, but also removes critical classes like sfTestBaseTask or sfTester from all git exports and thus composer packaging.
I think the line should be changed to /test/ to only match the actual symfony1 tests that can be safely ignored.