shutil.rmtree() raises in fake filesystem with Python 3.7

[mrbean-bremen]

This came up in the latest Travis.CI build: all shutil.rmtree() tests fail like this:

ERROR: test_rmtree (tests.fake_filesystem_shutil_test.FakeShutilModuleTest)
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Traceback (most recent call last):
  File "/home/travis/build/jmcgeheeiv/pyfakefs/tests/fake_filesystem_shutil_test.py", line 69, in test_rmtree
    shutil.rmtree(directory)
  File "/home/travis/virtualenv/python3.7-dev/lib/python3.7/shutil.py", line 485, in rmtree
    _rmtree_safe_fd(fd, path, onerror)
  File "/home/travis/virtualenv/python3.7-dev/lib/python3.7/shutil.py", line 400, in _rmtree_safe_fd
    with os.scandir(topfd) as scandir_it:
  File "/home/travis/build/jmcgeheeiv/pyfakefs/pyfakefs/fake_filesystem.py", line 3574, in scandir
    return scandir(self.filesystem, path)
  File "/home/travis/build/jmcgeheeiv/pyfakefs/pyfakefs/fake_scandir.py", line 156, in scandir
    return ScanDirIter(filesystem, path)
  File "/home/travis/build/jmcgeheeiv/pyfakefs/pyfakefs/fake_scandir.py", line 104, in __init__
    self.path = self.filesystem.ResolvePath(path)
  File "/home/travis/build/jmcgeheeiv/pyfakefs/pyfakefs/deprecator.py", line 50, in _new_func
    return func(*args, **kwargs)
  File "/home/travis/build/jmcgeheeiv/pyfakefs/pyfakefs/deprecator.py", line 67, in _old_function
    return func(*args, **kwargs)
  File "/home/travis/build/jmcgeheeiv/pyfakefs/pyfakefs/fake_filesystem.py", line 1865, in resolve_path
    file_path = os.fspath(file_path)
TypeError: expected str, bytes or os.PathLike object, not int