This makes the behaviour consistent with what happens if a date can
be extracted from the certificate but is expired.

This prevents valgrind from reporting possibly lost memory that NSPR
uses for file descriptor cache and other globally allocated internal
data structures.

This feature was unintentionally disabled by commit ff92fcfb.

... due to calling SSL_VersionRangeGet() with NULL file descriptor

reported-by: upstream tests 305 and 404

Possibly the final update before release...

... 'WWW-Authenticate: Negotiate' received from server

Reported by: David Woodhouse
Bug: https://bugzilla.redhat.com/1093348