Trac
Official site
Comments:
- Quick, flexible and customisable. The Bitten continuous integration plugin (http://bitten.edgewall.org/) works really well for Python projects too.
- Doesn't work as well for projects that don't use SVN. We use Git and we ended up having to replace it with a Git-web plugin of our own invention
Start-ups using:
- WebMynd
- GroupSpaces
- Smarkets
- CogniDox