Double lock

May result in immediate deadlock. Attempt to acquire a non-recursive lock that is already held
/src/mongo/db/repl/initial_syncer.cpp:1114: LOCK 155068 "unique_lock" locks "this->_mutex". [Note: The source code implementation of the function has been overridden by a builtin model.]
/src/mongo/db/repl/initial_syncer.cpp:1114: LOCK 155068 "lock" and "this->_mutex" point to the same lock. [Note: The source code implementation of the function has been overridden by a builtin model.]