Regular failure of test_http_connection_range about asdf HOT 6 CLOSED

$ pytest asdf/tests/test_generic_io.py::test_http_connection_range --remote-data -v
================================================== test session starts ==================================================
platform darwin -- Python 3.9.0, pytest-6.1.2, py-1.9.0, pluggy-0.13.1 -- /Users/jdavies/miniconda3/envs/asdf/bin/python
cachedir: .pytest_cache
rootdir: /Users/jdavies/dev/asdf, configfile: setup.cfg
plugins: doctestplus-0.8.0, remotedata-0.3.2, openfiles-0.5.0, asdf-2.8.0.dev103+g89947dd.d20201112
collected 2 items                                                                                                       

asdf/tests/test_generic_io.py::test_http_connection_range[create_small_tree] PASSED                               [ 50%]
asdf/tests/test_generic_io.py::test_http_connection_range[create_large_tree] FAILED                               [100%]

======================================================= FAILURES ========================================================
_____________________________________ test_http_connection_range[create_large_tree] _____________________________________

tree = {'more': array([[[0.46697203, 0.26663249, 0.31253938, ..., 0.42559718,
         0.05273264, 0.19073801],
        [0.61...1,
        0.08548561],
       [0.20447504, 0.64278415, 0.44272929, ..., 0.53209797, 0.99239067,
        0.73564929]])}
rhttpserver = <asdf.tests.httpserver.RangeHTTPServer object at 0x7f8b08477250>

    @pytest.mark.remote_data
    def test_http_connection_range(tree, rhttpserver):
        path = os.path.join(rhttpserver.tmpdir, 'test.asdf')
        connection = [None]
    
        def get_write_fd():
            return generic_io.get_file(open(path, 'wb'), mode='w')
    
        def get_read_fd():
            fd = generic_io.get_file(rhttpserver.url + "test.asdf")
            assert isinstance(fd, generic_io.HTTPConnection)
            connection[0] = fd
            return fd
    
        with _roundtrip(tree, get_write_fd, get_read_fd) as ff:
            if len(tree) == 4:
                assert connection[0]._nreads == 0
            else:
>               assert connection[0]._nreads == 6
E               assert 5 == 6
E                 +5
E                 -6

asdf/tests/test_generic_io.py:296: AssertionError
------------------------------------------------- Captured stderr call --------------------------------------------------
127.0.0.1 - - [12/Nov/2020 15:20:58] "GET /test.asdf HTTP/1.1" 206 -
127.0.0.1 - - [12/Nov/2020 15:20:58] "GET /test.asdf HTTP/1.1" 206 -
127.0.0.1 - - [12/Nov/2020 15:20:58] "GET /test.asdf HTTP/1.1" 206 -
127.0.0.1 - - [12/Nov/2020 15:20:58] "GET /test.asdf HTTP/1.1" 206 -
127.0.0.1 - - [12/Nov/2020 15:20:58] "GET /test.asdf HTTP/1.1" 206 -
127.0.0.1 - - [12/Nov/2020 15:20:58] "GET /test.asdf HTTP/1.1" 206 -
================================================ short test summary info ================================================
FAILED asdf/tests/test_generic_io.py::test_http_connection_range[create_large_tree] - assert 5 == 6
============================================== 1 failed, 1 passed in 0.87s ==============================================