NSS: do not skip cache check for netgoups
When refresh_expired_interval was not zero,
the NSS responder only refreshed netgroup cache
using background periodic task and ignored
SYSDB_CACHE_EXPIRE attribute.
With this behaviour it was impossible to
get new netgroup from remote server even
after sss_cache tool was used to expire
existing entry in the cache.
Resolves:
https://fedorahosted.org/sssd/ticket/2912
Reviewed-by: Pavel Březina <pbrezina@redhat.com>