tests/installed: Add var-mount.yml destructive test

Closes: #1668
Approved by: cgwalters

tests/installed/destructive/var-mount.yml

@@ -0,0 +1,13 @@
+# https://github.com/ostreedev/ostree/issues/1667
+- name: Set up /var as a mountpoint
+  shell: |
+    set -xeuo pipefail
+    cp -a /var /sysroot/myvar
+    touch /sysroot/myvar/somenewfile
+    echo '/sysroot/myvar /var none bind 0 0' >> /etc/fstab
+- include_tasks: ../tasks/reboot.yml
+- name: Check that /var mountpoint worked
+  shell: |
+    set -xeuo pipefail
+    systemctl status var.mount
+    test -f /var/somenewfile