ImportHandler: early return by condition inversion
ImportHandler: early return by condition inversion

No functional changes

aptivate/etherpad-lite,ether/etherpad-lite,joequant/etherpad-lite,storytouch/etherpad-lite,storytouch/etherpad-lite,joequant/etherpad-lite,cloudfoundry-community/etherpad-lite-cf,aptivate/etherpad-lite,storytouch/etherpad-lite,joequant/etherpad-lite,joequant/etherpad-lite,aptivate/etherpad-lite,cloudfoundry-community/etherpad-lite-cf,ether/etherpad-lite,cloudfoundry-community/etherpad-lite-cf,ether/etherpad-lite,cloudfoundry-community/etherpad-lite-cf,aptivate/etherpad-lite