Bug 663752 - Cert renewal for attrcrypt and encchangelog
https://bugzilla.redhat.com/show_bug.cgi?id=663752
Description: When changelog is encrypted and the certificate
used for the encryption has a problem (e.g., expired, renewed,
etc.), running the CL2LDIF task could crash the server. This
patch is adding more error checks for the decrypted result.
If a problem is found, it skips the change.
(cherry picked from commit c35e240ff8a65225b8e1f890ccdc54da7533dbcf)