Because powerline depends on python-powerline (the python2 version) and recommends python3-powerline (python3) so both end up getting installed.
$ apt-cache show powerline Package: powerline Architecture: amd64 Version: 2.6-1 Priority: optional Section: universe/python Origin: Ubuntu Maintainer: Ubuntu Developers <email address hidden> Original-Maintainer: Jerome Charaoui <email address hidden> Bugs: https://bugs.launchpad.net/ubuntu/+filebug Installed-Size: 251 Depends: python:any (>= 2.7.5-5~), python-powerline Recommends: fonts-powerline, python3-powerline ...
Because powerline depends on python-powerline (the python2 version) and recommends python3-powerline (python3) so both end up getting installed.
$ apt-cache show powerline Maintainer: Jerome Charaoui <email address hidden> /bugs.launchpad .net/ubuntu/ +filebug
Package: powerline
Architecture: amd64
Version: 2.6-1
Priority: optional
Section: universe/python
Origin: Ubuntu
Maintainer: Ubuntu Developers <email address hidden>
Original-
Bugs: https:/
Installed-Size: 251
Depends: python:any (>= 2.7.5-5~), python-powerline
Recommends: fonts-powerline, python3-powerline
...