Not able to find ca and ra properly

[sharad]

when more than one certificates (different CA and RA) are returned by Client.get_ca_certs() functions.

the comparison

(cert.is_ca != ca_only)

will return True if

cert.is_ca == None ca_only == False

in

digital_sign = self._filter(required_key_usage=required, not_required_key_usage=not_required, ca_only=False)

return wrong certificate