fix pybb_get_profile return type consistency
fix pybb_get_profile return type consistency

when it is impossible to get the profile from the user,
this tag was returning an empty queryset (enum type)
instead a single object (None for this case).

hovel/pybbm,artfinder/pybbm,artfinder/pybbm,artfinder/pybbm,hovel/pybbm,hovel/pybbm