python 2.5, zlib 1.2.5 and failing make test

I needed to have Python 2.5 for an App Engine project. My test virtual machine is running Ubuntu 10.10 with Python 2.6.5 so I decided to install Python 2.5 and use virtualenv to manage different development projects. Obviously this wasn't going to be that simple. Firstly I installed Python 2.5 using a convenient staging area. I prefer /usr/local/src:-

$ cd /usr/local/src
$ sudo wget http://www.python.org/ftp/python/2.5.5/Python-2.5.5.tgz
$ sudo tar -xzf Python-2.5.5.tgz
$ cd Python-2.5.5
$ sudo ./configure --prefix=/usr/local/python2.5
$ sudo make
$ sudo make test

And I saw the first problem:-

test_zlib skipped -- No module named zlib

This meant I also had to install zlib:-

$ cd /usr/local/src
$ sudo wget http://zlib.net/zlib-1.2.5.tar.gz
$ sudo tar -zxf zlib-1.2.5.tar.gz
$ cd zlib-1.2.5
$ sudo ./configure
$ sudo make
$ sudo make install

This improved things a bit, but I still had a failure with the zlib test:-

test test_zlib failed -- Traceback (most recent call last):
File "/usr/local/src/Python-2.5.5/Lib/test/test_zlib.py", line 72, in test_baddecompressobj
self.assertRaises(ValueError, zlib.decompressobj, 0)
AssertionError: ValueError not raised

A bit more research showed that changes in zlib after 1.2.3 caused the zlib test to fail. Sadly the fix was not being backported to 2.5, meaning that I had to change the test manually:-

$ cd/usr/local/src/Python-2.5.5/Lib/test
$ sudo joe test_zlib.py

Go to line 72, change 0 to -1 on that line, save and exit.

Now the zlib test passed, and Python 2.5 can be installed:-

$ cd /usr/local/src/Python-2.5.5
$ sudo make install