Refactoring some negative conditionals in mp_tree
Refactoring some negative conditionals in mp_tree

django-treebeard/django-treebeard,tabo/django-treebeard,skirsdeda/django-treebeard,skirsdeda/django-treebeard,tabo/django-treebeard,skirsdeda/django-treebeard,tabo/django-treebeard,django-treebeard/django-treebeard,tabo/django-treebeard,skirsdeda/django-treebeard,django-treebeard/django-treebeard