copr: builders: better tweak mock-core-configs

We first run the copr-update-builder script, so it does it's work.
Then we can try to update to our own (newer only!) version of
mock-core-configs, and re-run the copr-update-builder.

We though have to stop removing the old .rpmnew files blindly, this
needs patch against copr/copr.git.

roles/copr/backend/files/provision/provision_builder_tasks.yml

@@ -18,13 +18,6 @@
   shell: dnf -y upgrade
   when: prepare_base_image is defined
 
-- name: install the latest mock and mock-core-configs from updates-testing
-  package: state=present name={{ packages }}
-  vars:
-    packages:
-    - https://kojipkgs.fedoraproject.org/packages/mock/2.2/1.fc31/noarch/mock-2.2-1.fc31.noarch.rpm
-    - https://kojipkgs.fedoraproject.org/packages/mock-core-configs/32.6/1.fc31/noarch/mock-core-configs-32.6-1.fc31.noarch.rpm
-
 - name: enable copr repo in staging
   command:
     cmd: dnf copr -y enable {{ item }}
@@ -74,9 +67,24 @@
   when:
   - prepare_base_image is not defined
 
+- name: don't remove rpmnew files, but always use them
+  lineinfile: state=absent regexp='^find /etc/mock.*-delete'
+
 - name: run /bin/copr-update-builder from copr-builder package
   shell: /usr/bin/copr-update-builder
 
+- name: install the latest mock and mock-core-configs from updates-testing
+  package: state=latest name={{ packages }}
+  register: mock_updated
+  vars:
+    packages:
+    - https://kojipkgs.fedoraproject.org/packages/mock/2.2/1.fc31/noarch/mock-2.2-1.fc31.noarch.rpm
+    - https://kojipkgs.fedoraproject.org/packages/mock-core-configs/32.6/1.fc31/noarch/mock-core-configs-32.6-1.fc31.noarch.rpm
+
+- name: re-run copr-update builder when mock/mock-core-configs are updated
+  shell: /usr/bin/copr-update-builder
+  when: mock_updated.changed
+
 - name: put copr-rpmbuild configuration file in the right place
   copy: src=files/main.ini dest=/etc/copr-rpmbuild/main.ini