Python GnuPGInterface

I'm running duplicity, which calls GnuPGInterface to encrypt its backup
files. I'm running Python 2.5 and GnuPGInterface 0.3.2, so I think I have
the latest releases. The underlying OS is Mac OS X 10.4.10.

The problem appears to be that a pipe call fails with an error OSError:
[Errno 24] Too many open files. I'm guessing that duplicity or
GnuPGInterface isn't closing pipes it should, which doesn't matter on most
systems but does here, but I don't know python well enough to know where to
start to look for this.

The program fails with the following error:

.....
Running 'scp -oUserKnownHostsFile=/dev/null -oStrictHostKeyChecking=no
/tmp/tmp0uHsAr
x@y:backup/hourly/duplicity-inc.2007-12-10T00:33:02-04:00.to.2007-12-13T10:
02:06-04:00.vol1.difftar.gpg' (attempt #1)
Traceback (most recent call last):
File "/usr/local/bin/duplicity", line 378, in <module>
if __name__ == "__main__": main()
File "/usr/local/bin/duplicity", line 372, in main
else: incremental_backup(sig_chain)
File "/usr/local/bin/duplicity", line 175, in incremental_backup
bytes_written = write_multivol("inc", tarblock_iter, globals.backend)
File "/usr/local/bin/duplicity", line 83, in write_multivol
globals.gpg_profile,globals.volsize)
File "/usr/local/lib/python2.5/site-packages/duplicity/gpg.py", line 193,
in GPGWriteFile
File "/usr/local/lib/python2.5/site-packages/duplicity/gpg.py", line 100,
in __init__
File
"/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/site-packa
ges/GnuPGInterface.py", line 357, in run
create_fhs, attach_fhs)
File
"/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/site-packa
ges/GnuPGInterface.py", line 388, in _attach_fork_exec
pipe = os.pipe()
OSError: [Errno 24] Too many open files
gpg: Error writing to `-': Broken pipe
gpg: handle plaintext failed: file write error
gpg: Error writing to `-': Broken pipe
gpg: handle plaintext failed: file write error
gpg: Error writing to `-': Broken pipe
gpg: handle plaintext failed: file write error
gpg: Error writing to `-': Broken pipe
gpg: handle plaintext failed: file write error
(and so on...)