Mathias Ertl submitted
Python 3 patches
to the Fabric maintainer. These patches stopped compatibility with
Python 2.5 and earlier, so the Fabric maintainer did not accept them.
Mathias forked the code and
released the fork to pypi.
It can be installed with
pip install Fabric3.
There is a problem in Fedora packaging, not necessarily with the software itself. See the linked Fedora bug.