Update: The below no longer applies. A fix has been released. (So you can undo any ugly hack you used in order to make it work.)

Dear Python developers,

when upgrading to Ubuntu 9.04 (Jaunty Jackalope, which is to be released in 22 days from now) please keep in mind that python-virtualenv (the tool we all know and love) is broken. It still works with python2.5, though.

While trying to resolve this issue I had several ideas:

• Deinstall python2.6 so python2.5 is used instead. This turned out to be a bad idea.
• Some may be used to update-alternatives. This can’t be used for python.
• If you just change the symlink /usr/bin/python from /usr/bin/python2.6 to /usr/bin/python2.5 it will first seem to work, but some tasks will fail. E.g. when installing python2.5-dev, you will get the following error: ValueError: /usr/bin/python does not match the python default version. It must be reset to point to python2.6
• You then need to do another ugly workaround.

I am not sure whether this will wreak further havoc, so please be cautious. I hope that we can get this fixed until Jaunty is released. There is a bug report.

Just letting you know. Took me some time to realize.