It's possible for lookupNSSbyUUID to fail to find a collection's NSS from its UUID on the donor after a moveCollection .

Example 1:
This breaks the AutoGetCollection* helpers. AutoGetCollection* accept a NamespaceStringOrUUID, and so when a UUID is provided, the first step is to resolve the UUID to a NSS so that the lock can be grabbed.

Essentially because UUID -> NSS resolution can fail, what should've been a StaleConfig (or other sharding staleness error) due to the moveCollection will now manifest as a NamespaceNotFound because we were unable to find the UUID, which is incorrect.

There may be other cases besides AutoGetCollection* where the existing behavior is problematic. See comments and linked BF / tickets for more info and examples. The examples listed below are not exhaustive.