The changed test passes on 3.4 branch, but fails on 2.7 branch:

$ python2.7 -m test.test_audioop
test_add (__main__.TestAudioop) ... ok
test_adpcm2lin (__main__.TestAudioop) ... ok
test_alaw2lin (__main__.TestAudioop) ... ok
test_avg (__main__.TestAudioop) ... ok
test_avgpp (__main__.TestAudioop) ... ok
test_bias (__main__.TestAudioop) ... ok
test_cross (__main__.TestAudioop) ... ok
test_findfactor (__main__.TestAudioop) ... ok
test_findfit (__main__.TestAudioop) ... ok
test_findmax (__main__.TestAudioop) ... ok
test_getsample (__main__.TestAudioop) ... ok
test_issue7673 (__main__.TestAudioop) ... ok
test_lin2adpcm (__main__.TestAudioop) ... ok
test_lin2alaw (__main__.TestAudioop) ... ok
test_lin2lin (__main__.TestAudioop) ... ok
test_lin2ulaw (__main__.TestAudioop) ... ok
test_max (__main__.TestAudioop) ... ok
test_maxpp (__main__.TestAudioop) ... ok
test_minmax (__main__.TestAudioop) ... ok
test_mul (__main__.TestAudioop) ... ok
test_negativelen (__main__.TestAudioop) ... ok
test_ratecv (__main__.TestAudioop) ... ERROR
test_reverse (__main__.TestAudioop) ... ok
test_rms (__main__.TestAudioop) ... ok
test_tomono (__main__.TestAudioop) ... ok
test_tostereo (__main__.TestAudioop) ... ok
test_ulaw2lin (__main__.TestAudioop) ... ok
test_wrongsize (__main__.TestAudioop) ... ok

======================================================================
ERROR: test_ratecv (__main__.TestAudioop)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/lib64/python2.7/test/test_audioop.py", line 304, in test_ratecv
    3: packs[3](0, 0x0da740, 0x377776, -0x262fca,
KeyError: 3

----------------------------------------------------------------------
Ran 28 tests in 0.009s

FAILED (errors=1)
Traceback (most recent call last):
  File "/usr/lib64/python2.7/runpy.py", line 162, in _run_module_as_main
    "__main__", fname, loader, pkg_name)
  File "/usr/lib64/python2.7/runpy.py", line 72, in _run_code
    exec code in run_globals
  File "/usr/lib64/python2.7/test/test_audioop.py", line 410, in <module>
    test_main()
  File "/usr/lib64/python2.7/test/test_audioop.py", line 407, in test_main
    run_unittest(TestAudioop)
  File "/usr/lib64/python2.7/test/test_support.py", line 1400, in run_unittest
    _run_suite(suite)
  File "/usr/lib64/python2.7/test/test_support.py", line 1383, in _run_suite
    raise TestFailed(err)
test.test_support.TestFailed: Traceback (most recent call last):
  File "/usr/lib64/python2.7/test/test_audioop.py", line 304, in test_ratecv
    3: packs[3](0, 0x0da740, 0x377776, -0x262fca,
KeyError: 3