[travis-ci] Workaround composer cache invalidation
[travis-ci] Workaround composer cache invalidation

see: https://github.com/travis-ci/travis-ci/issues/2435

weierophinney/zend-http,zendframework/zend-http,netroby/zend-http,malinink/zend-http,Maks3w/zend-http,asgrim/zend-http