The following code:
echo -n Testing123 | bzip2 > test.bz2
python -c "import bz2; lines =
bz2.BZ2File('test.bz2').readlines()"

produces this output:
Traceback (most recent call last):
  File "<string>", line 1, in ?
RuntimeError: wrong sequence of bz2 library commands used

Tested on Python 2.4.1 (debian unstable - April 1
2005), and Python 2.3.5 (debian unstable - May 26 2005)

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The looks like correct behavior to me.  The test.bz2 file is
not in a valid bz2 format.  I suspect that you've misread
the BZ2File API which is intended for reading and writing
uncompressed data to and from a file in a bz2 format (where
the data is stored in compressed form).

If this interpretation of the bug report is correct, please
mark as not-a-bug and close.

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How is test.bz2 not a valid bz2 file?  The command line tool
"bzcat" or "bunzip2" can operate properly on it.  Using
BZ2File("test.bz2").read() works properly, it's just the
readlines() call that breaks.

Try this out:
import bz2
bz2.BZ2File("test.bz2","w").write("testing123")

# This works fine
assert bz2.BZ2File("test.bz2").read() == "testing123"

# This raises a RuntimeError
assert bz2.BZ2File("test.bz2").readlines() == ["testing123"]

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Okay, I see.  Will look into it.

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Calling .readline() works fine, though.  The problem wasn't
apparent with a quick look at the readlines() code.

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Reinhold, do you want to take this one?

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Fixed, also for xreadlines(). Problem was that the code, if
there were no newlines in a chunk read from the file,
assumed that the buffer was too small.

Modules/bz2module.c r1.25
Lib/test/test_bz2.py r1.18

Please review the fix!