Regarding the issue J. David Ibáñez has, I have a few comments to add:

- It's also present on 32bit.
- AFAICT:
  * it's present in both 2.6 branch & trunk (as of 68886),
  * it's a problem with line 1110 (in 2.6 branch), or line 1122 in
trunk, which should read "<LLL" instead of "<lLL",
  * it is an omission from changeset 61591: 
http://svn.python.org/view/python/trunk/Lib/zipfile.py?view=diff&r1=61590&r2=61591
which changed line 964 (at the time)
http://svn.python.org/view/python/trunk/Lib/zipfile.py?annotate=61591#l964
but not the corresponding one in writestr.

I'm not sure whether or not a separate bug report should be opened for
this issue.