Assignment operator does not check for self-assignment

Defect 73711 (STATIC_C)
Checker SELF_ASSIGN (subcategory none)
File: /src/mongo/executor/network_test_env.h
Function mongo::executor::NetworkTestEnv::FutureHandle<void>::operator =(mongo::executor::NetworkTestEnv::FutureHandle<void>&&)
/src/mongo/executor/network_test_env.h, line: 87
No protection against the object assigning to itself.

                _executor = other._executor;