I was upgrading from 13.10 to 14.04 (dev for now, stable in a few hours) using do-release-upgrade and encountered the following problem:
Can not upgrade
Your python install is corrupted. Please fix the '/usr/bin/python' symlink.
I solved the problem after messing around a bit, so I'd like to share my solution here. Hope this could help someone.
My problem turned out to be solely due to an altered /usr/bin/python symlink as suggested in the error message. I was using update-alternatives with /usr/bin/python so it was pointing to /etc/alternatives/python. Turned out that do-release-upgrade is really strict with this symlink and merely selecting python2.7 with update-alternatives isn't enough, so I ended up forcing it to its original state:
sudo ln -sf /usr/bin/python2.7 /usr/bin/python
And that solved the problem.
If this doesn't work for you, then I guess you have a genuinely corrupted python install. I'd suggest
sudo apt-get install --reinstall python
