Fixed #27462 -- Clarifed pk_set difference in m2m_changed signal receivers for add() and remove().
Fixed #27462 -- Clarifed pk_set difference in m2m_changed signal receivers for add() and remove().

Thank you to Mariusz Felisiak for review.

takis/django,takis/django,dsanders11/django,googleinterns/django,MarkusH/django,shaib/django,django/django,georgemarshall/django,takis/django,claudep/django,georgemarshall/django,shaib/django,dsanders11/django,georgemarshall/django,simonw/django,ghickman/django,atul-bhouraskar/django,blighj/django,koordinates/django,blighj/django,freakboy3742/django,pauloxnet/django,theo-l/django,claudep/django,auvipy/django,MarkusH/django,felixxm/django,googleinterns/django,shaib/django,monetate/django,georgemarshall/django,rsalmaso/django,felixxm/django,pauloxnet/django,MarkusH/django,simonw/django,felixxm/django,wkschwartz/django,manhhomienbienthuy/django,claudep/django,koordinates/django,django/django,takis/django,pauloxnet/django,monetate/django,manhhomienbienthuy/django,elena/django,django/django,elena/django,theo-l/django,koordinates/django,monetate/django,solarissmoke/django,shaib/django,auvipy/django,auvipy/django,monetate/django,adamchainz/django,theo-l/django,solarissmoke/django,django/django,koordinates/django,adamchainz/django,googleinterns/django,adamchainz/django,kaedroho/django,atul-bhouraskar/django,simonw/django,auvipy/django,manhhomienbienthuy/django,blighj/django,elena/django,ghickman/django,simonw/django,claudep/django,wkschwartz/django,ghickman/django,apollo13/django,googleinterns/django,wkschwartz/django,adamchainz/django,kaedroho/django,rsalmaso/django,freakboy3742/django,dsanders11/django,apollo13/django,atul-bhouraskar/django,apollo13/django,pauloxnet/django,felixxm/django,kaedroho/django,solarissmoke/django,rsalmaso/django,blighj/django,ghickman/django,theo-l/django,solarissmoke/django,wkschwartz/django,dsanders11/django,elena/django,rsalmaso/django,atul-bhouraskar/django,MarkusH/django,apollo13/django,manhhomienbienthuy/django,freakboy3742/django