PathListingWidget : Fix GIL management bug
PathListingWidget : Fix GIL management bug

This could trigger a hang when shift+clicking to expand a whole section of the HierarchyView.

johnhaddon/gaffer,andrewkaufman/gaffer,appleseedhq/gaffer,johnhaddon/gaffer,GafferHQ/gaffer,johnhaddon/gaffer,andrewkaufman/gaffer,appleseedhq/gaffer,ImageEngine/gaffer,lucienfostier/gaffer,lucienfostier/gaffer,lucienfostier/gaffer,ImageEngine/gaffer,GafferHQ/gaffer,GafferHQ/gaffer,boberfly/gaffer,GafferHQ/gaffer,andrewkaufman/gaffer,appleseedhq/gaffer,ImageEngine/gaffer,hradec/gaffer,johnhaddon/gaffer,appleseedhq/gaffer,hradec/gaffer,lucienfostier/gaffer,boberfly/gaffer,andrewkaufman/gaffer,hradec/gaffer,ImageEngine/gaffer,boberfly/gaffer,hradec/gaffer,GafferHQ/gaffer,johnhaddon/gaffer,hradec/gaffer,boberfly/gaffer,andrewkaufman/gaffer