Buildbots failing after reintegration of diff-optimizations-bytes

Apparently I broke the builds on the builtbots yesterday evening,
after integrating the diff-optimizations-bytes branch. Sorry for that.

There were two problems:
- Failing diff-diff3-test.exe (actually hanging). This was rectified
in r1067839.

- Failing (python) bindings. I could use some help with that (I don't
understand how these are generated, and where/what I should change).
This is the relevant excerpt from stdio from svn-x64-centos gcc:

[[[
subversion/bindings/swig/python/svn_diff.c: In function
'svn_diff_fns2_invoke_datasources_open':
subversion/bindings/swig/python/svn_diff.c:2838: warning: passing
argument 3 of '_obj->datasources_open' makes pointer from integer
without a cast
subversion/bindings/swig/python/svn_diff.c:2838: error: too few
arguments to function '_obj->datasources_open'
subversion/bindings/swig/python/svn_diff.c:2839: warning: control
reaches end of non-void function
]]]

Can someone, more knowledgeable than me with the bindings, take a look
at this and/or give me a pointer for what I should do?

If this is a major problem, blocking someone from doing their work:
feel free to revert whatever is needed.

Thanks,

-- 
Johan