It would be nice if there was a way to tell compilers not to drop the lock stack and thus issue warnings when accessing a symbol that needs a lock inside `Assume`/`Assert`.

Hit by (at least): @ajtowns , @jnewbery , me.
{
    char ch;
    while (true) {
        int rv = read(fd, &ch, 1); 
        assert(rv == 1);
        switch(ch) {
        case LockCommand:
            ch = LockDirectory(dirname, lockname);
            rv = write(fd, &ch, 1);
            assert(rv == 1);
            break;
        case UnlockCommand:
            ReleaseDirectoryLocks();
            ch = true; 
            rv = write(fd, &ch, 1);
            assert(rv == 1);
            break;
        case ExitCommand:
            close(fd);
            exit(0);
        default:
            assert(0);
        }
    }
}
#endif
BOOST_AUTO_TEST_CASE(test_LockDirectory)