Current advice
It seems there is already official support for Python 3.4+ in Fabric v2+ and I guess it should be preferred although there may be some incompatible changes. So in an ideal world, nobody should have this problem anymore 🙂
pip3 install -U "fabric>2.0"
Maintained old API in Python 3
Because some people were happy with the old API of the Fabric, there is a maintained fork supporting Python 3 called fab-classic. See also discussion in the Github issue Recreating the Fabric 1 API in Fabric 2?
The previous advice
There is Python3 port of Fabric named Fabric3 which supports Python 2.7 and 3.4+ (dropped support for Python <2.7). I use it some time as a replacement and it works for me without any issues.
pip3 install fabric3