[testlib] fix page validator selection. Closes #2869456
* use a validator that checks XML well-formness for the html5 doctype
(as a convenient side-effect, it does not choke on e.g. a canvas tag
like the HTMLParser does)
* use a DTD validator if there is an xml declaration
* else use the HTMLValidator
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',)}