In find_certificate_by_callback, function return -1 directly without
free resource if node is null, that will lead to nss shut down failed.
The error message as below:
could not shut down NSS: NSS could not shutdown. Objects are still in use.
To fix this issue, free all resources before function return -1.
References: bsn#381
Signed-off-by: Chenxi Mao <chenxi.mao@suse.com>
