The mockito people thought it was a good idea to use a distribute bootstrapping script that downloads distribute-0.6.10.tar.gz from PyPI and then tries to use that for the setup.
They were wrong.
Mockito is unusable on python3 because of this and pip installs will fail with
error: invalid command 'bdist_egg'
There is a pull request pending at bitbucket (yes the sources are on bitbucket, not on code.google.com like the metadata on PyPI pretends) but there's been no activity up until now.
You can use this project (which is on PyPI) until the pull request is merged. Just replace
pip install mockito
with
pip install mockito-without-hardcoded-distribute-version
You don't need to change anything else. This will work on python 2 and 3.