fix handling of delorean on non-x86

Python 2.7.5 != 2.7.9 when it comes to handling None. So sort disabling
delorean-deps.repo on non-x86 in other way.

Change-Id: Iae86c391c7dcf006538d39d9b447f47171b8b541
Partially-Implements: blueprint multiarch-and-arm64-containers

kolla/common/config.py

@@ -45,8 +45,8 @@ DELOREAN = \
 #            there is ongoing work to sort that out
 DELOREAN_DEPS = {
     'x86_64': "https://trunk.rdoproject.org/centos7/delorean-deps.repo",
-    'aarch64': None,
-    'ppc64le': None
+    'aarch64': "",
+    'ppc64le': ""
 }
 
 INSTALL_TYPE_CHOICES = ['binary', 'source', 'rdo', 'rhos']

kolla/image/build.py

@@ -622,7 +622,7 @@ class KollaWorker(object):
                 else:
                     # Copy .repo file from filesystem
                     cmd = "COPY {} /etc/yum.repos.d/".format(config)
-            elif config is None:
+            elif not config:
                 cmd = ''
             else:
                 raise exception.KollaRpmSetupUnknownConfig(