MB-11980: Add sanity checks for setting current snapshot

This change will help with debugging the issue linked above. We
are merging this into the 3.0 branch since the toy builders are
down and we want to resolve this issue as soon as possible. It
will be reverted if it causes any major issues.

Change-Id: Ie4a357270b52bd35b5f29018f24fd3550913f1cc