Fix storing of zero value revocation timestamp

internal/x509/openssl/repository.go

@@ -69,12 +69,14 @@ type indexEntry struct {
 func (ie *indexEntry) String() string {
 	var revoked, fileName string
 
-	if ie.revokedAt != nil {
+	if ie.revokedAt != nil && !ie.revokedAt.IsZero() {
 		revoked = fmt.Sprintf("%s,%s", ie.revokedAt.Format(TimeSpec), ie.revocationReason)
 	}
 
 	if ie.fileName == "" {
 		fileName = "unknown"
+	} else {
+		fileName = ie.fileName
 	}
 
 	return strings.Join([]string{