patch: support unpickling UserPropertySheet instance that is pickled as old-style class.
this happens when a OAuth2 logged in user creates an activity on Zope2 then the system is upgraded to Zope4.
/cc @jerome @vpelletier
this happens when a OAuth2 logged in user creates an activity on Zope2 then the system is upgraded to Zope4.
/cc @jerome @vpelletier