force filter into a list for Python 3 compatibility
force filter into a list for Python 3 compatibility

bretthandrews/marvin,albireox/marvin,bretthandrews/marvin,albireox/marvin,albireox/marvin,sdss/marvin,bretthandrews/marvin,sdss/marvin,bretthandrews/marvin,albireox/marvin,sdss/marvin,sdss/marvin