[devtools] Avoid db_cache collisions and mis-loading
This is done by stopping to share the db_cache between
TestDataBaseHandler instances
It may seem overkill, but is the only way I could get it to work
properly. I think the whole db caching code needs some rework to better
work with different db handlers.
Closes #4601328
from cubicweb.schemas.base import in_group, CWSourceSchemaConfig
# copy __permissions__ to avoid modifying a shared dictionary
in_group.__permissions__ = in_group.__permissions__.copy()
in_group.__permissions__['read'] = ('managers',)
cw_for_source = CWSourceSchemaConfig.get_relation('cw_for_source')
cw_for_source.__permissions__ = {'read': ('managers', 'users'),
'add': ('managers',),
'delete': ('managers',)}