Allow open() 'name' parameter to be a ZipInfo object, which allows opening archive members with duplicate filenames.  Also allow read() 'name' parameter to be a ZipInfo object, as it calls open() directly.
I got sent a zip file which had duplicate names in it, and the only way I could see to extract it using zipfile.py was to apply this patch.
The infolist() and namelist() methods will return information for duplicate filenames, but the open() method takes only a name.
This patch also updated the docs for zipfile.py.
Python 2.1 -> 2.5 zipfile.py module does not have an open() method, but it would be trivial to backport this patch to enhance the read() method.
# Test:
# write() optionally warns, but still allows,
# creating duplicate file names:
import zipfile
zf = zipfile.ZipFile('dupzip.zip', 'w')
zf.debug = 1
zf.writestr('dupname', 'Hello')
zf.writestr('dupname', 'World')
zf.close()
# Print 'Hello' 'World'
zfr = zipfile.ZipFile('dupzip.zip', 'r')
for inf in zfr.infolist():
  print repr(zfr.read(inf))
zfr.close()

In the patch you commented "why is 'filepos' computed next? It's never
referenced." The answer is that back at r54152 (#1121142) the method was
rewrote removing any reference to 'filepos', but the patch author failed
to remove that line. Please remove it.

Updated to latest revision, and converted documentation part of the
patch to reST.
Removed the line that pointlessly computes 'filepos', as requested by
Scott Dial.
(Please excuse my reST, I'm new to it and it's getting late).

Thanks, reviewed, added tests and committed as r63499.