Allow builder to attempt krb if gssapi is available

Signed-off-by: Patrick Uiterwijk <patrick@puiterwijk.org>

builder/kojid

@@ -68,6 +68,11 @@ try:
 except ImportError:  # pragma: no cover
     krbV = None
 
+try:
+    import requests_kerberos
+except ImportError:  # pragma: no cover
+    requests_kerberos = None
+
 try:
     import librepo
     import io
@@ -6264,7 +6269,7 @@ if __name__ == "__main__":
             quit("Error: Unable to log in. Bad credentials?")
         except six.moves.xmlrpc_client.ProtocolError:
             quit("Error: Unable to connect to server %s" % (options.server))
-    elif krbV:
+    elif krbV or requests_kerberos:
         krb_principal = options.krb_principal
         if krb_principal is None:
             krb_principal = options.host_principal_format % socket.getfqdn()