When I drag and drop a method between two classes and two nautilus browser.
I get a DNU isDefault because package returns nil
This is due to the execution of RBUnpackageCOdeRule
isUnpackaged: anEntity
^ anEntity package isDefault
https://pharo.fogbugz.com/f/cases/16474/When-I-drag-and-drop-a-method-between-two-classes