Revert "(#6309) Ensure the correct device is mounted when managing mounts"

This reverts commit 6cb365a887d47606bdfae0ff540038b0c49b7451, which
fixed bug #6309 but introduced bug #6411. In addition, it conflicts
with a significant patch to the mount provider that addresses #4914.

After merging in the fix for #4914 I will determine whether bug #6309
still exists, and if so work on an improved fix for it.