Workaround NSS bug in associating private key to certificate
If NSS uses SQL DB storage, CERT_ImportCerts creates incomplete
internal state (the cert isn't associated with the private key,
and calling PK11_FindKeyByAnyCert returns no result).
As a workaround, we import the cert again using PK11_ImportCert
which magically fixes the issue.
See rhbz#1532188
Related: https://pagure.io/certmonger/issue/88