tests: Fix installed tests more

OK so I noticed that something was failing and we were missing
`set -xeuo pipefail` in our shells.  That of course revealed
the ansible tests didn't actually work - my only defense
here is spending so much time fighting to get it through CI
and trying something new.

Anyways, to make the staged-deploy tests work we need a task
that actually uses `rpm-ostree override` rather than `usroverlay`.

Let's make this a bit saner and have a clean split between
tests that are "shell-script+usroverlay" and "ansible+override".

Closes: #1577
Approved by: jlebon

tests/installed/tasks/install-git.yml

@@ -0,0 +1,19 @@
+# Use package layering to install git builds.
+- command: ostree --version
+  changed_when: False
+  register: ostree_orig_version
+- set_fact:
+    ostree_orig_version_yaml: "{{ ostree_orig_version.stdout | from_yaml }}"
+- name: Copy locally built RPMs
+  synchronize: src=build/x86_64/ dest=/root/x86_64/ archive=yes
+- name: Install RPMs
+  shell: rpm-ostree override replace /root/x86_64/*.rpm
+- include_tasks: ../tasks/reboot.yml
+- command: ostree --version
+  register: ostree_new_version
+- set_fact:
+    ostree_new_version_yaml: "{{ ostree_new_version.stdout | from_yaml }}"
+- name: "Fail if we didn't change the ostree version"
+  when: ostree_orig_version_yaml['libostree']['Git'] == ostree_new_version_yaml['libostree']['Git']
+  fail:
+    msg: "Failed to change ostree version"