1. A variation of LockerImpl::lockGlobal passes in a nullptr for opCtx and is only used in unit tests. All of the production callers use a variation of LockerImpl::lockGlobal that takes a real opCtx.

This would requiring setting up an opCtx for the locking unit tests. It is trivial to add it to d_concurrency_test.cpp unit tests as opCtx is already available in other unit tests using the same test fixture. lock_state_test.cpp, however, just uses ServiceContextTest, which does not set up an opCtx: we would have to add an opCtx to the test fixture.