Fix image registry conditional

`kolla_docker_registry` evaluates to an empty string if neither
a docker or podman registry are configured. This leads to broken
behaviour if an image build is attempted with a regex specified.

Closes-bug: #2112646

Change-Id: I4548410d533731138de02780dc8b2013e71730d0

ansible/container-image-build.yml

@@ -53,7 +53,7 @@
           kolla-build
           --config-dir {{ kolla_build_config_path }}
           --engine {{ container_engine }}
-          {% if kolla_docker_registry is not none %}--registry {{ kolla_docker_registry }}{% endif %}
+          {% if kolla_docker_registry %}--registry {{ kolla_docker_registry }}{% endif %}
           {% if push_images | bool %}--push{% endif %}
           {% if nocache | bool %}--nocache{% endif %}
           {% if kolla_base_arch != ansible_facts.architecture %}--platform {{ platform }}{% endif %}

releasenotes/notes/fix-empty-registry-bug.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    Fixes an issue building images with a regex when no image registry is set
+    `LP#2112646 <https://bugs.launchpad.net/kayobe/+bug/2112646>`__