Prevent rescuing a VM with a partially mounted volume.

If a VM goes into rescue mode with a partially mounted volume, the
volume won't re-appear after the VM is unrescued.

Fix bug 1158942

Change-Id: I1e104236c41c59e67a0f0e9ef26143c57f6e0094
Merge "Prevent rescuing a VM with a partially mounted volume."
Merge remote-tracking branch 'm_src_repo/citrix-fixes' into build-temp