Fix failure to parse DER encoded cert

BUG: https://bugzilla.suse.com/show_bug.cgi?id=1196658

Signed-off-by: David Mulder <[email protected]>

cepces/core.py

@@ -282,10 +282,17 @@ def _resolve_chain(self, data, child=None):
         oid = x509.oid.AuthorityInformationAccessOID
 
         # Load the certificate.
-        cert = x509.load_pem_x509_certificate(
-            data.encode(),
-            default_backend(),
-        )
+        try:
+            cert = x509.load_pem_x509_certificate(
+                data.encode(),
+                default_backend(),
+            )
+        except ValueError:
+            # The cert may be DER encoded instead
+            cert = x509.load_der_x509_certificate(
+                data.encode(),
+                default_backend(),
+            )
 
         # If no child is present, this is the first cert and thus cannot be
         # verified yet.