test_buffered_reader test_gzip is failing for me since r80720, on trunk on OS X 10.6.3:

======================================================================
ERROR: test_buffered_reader (__main__.TestGzip)
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Traceback (most recent call last):
  File "Lib/test/test_gzip.py", line 91, in test_buffered_reader
    lines = [line for line in r]
  File "/Users/dickinsm/python/svn/trunk/Lib/gzip.py", line 365, in flush
    self.fileobj.flush()
IOError: [Errno 9] Bad file descriptor

----------------------------------------------------------------------
Ran 16 tests in 1.258s

FAILED (errors=1)
Traceback (most recent call last):
  File "Lib/test/test_gzip.py", line 271, in <module>
    test_main(verbose=True)
  File "Lib/test/test_gzip.py", line 268, in test_main
    test_support.run_unittest(TestGzip)
  File "/Users/dickinsm/python/svn/trunk/Lib/test/test_support.py", line 1038, in run_unittest
    _run_suite(suite)
  File "/Users/dickinsm/python/svn/trunk/Lib/test/test_support.py", line 1021, in _run_suite
    raise TestFailed(err)
test.test_support.TestFailed: Traceback (most recent call last):
  File "Lib/test/test_gzip.py", line 91, in test_buffered_reader
    lines = [line for line in r]
  File "/Users/dickinsm/python/svn/trunk/Lib/gzip.py", line 365, in flush
    self.fileobj.flush()
IOError: [Errno 9] Bad file descriptor


Here's a minimal Python script that produces the failure:

import gzip
import io

f = gzip.GzipFile('hamster', 'wb')
f.write("some data")
f.close()

f = gzip.GzipFile('hamster', 'rb')
r = io.BufferedReader(f)
lines = [line for line in r]
r.close()

This gives the following output:

Traceback (most recent call last):
  File "test_gzip.py", line 11, in <module>
    r.close()
  File "/Users/dickinsm/python/svn/trunk/Lib/gzip.py", line 365, in flush
    self.fileobj.flush()
IOError: [Errno 9] Bad file descriptor
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