since commit a0739c9423a4c559b45af96fa4cdb30539dcdbd7, horizon use
a pure Python alternative to nodejs
Change-Id: I231b453e42c303c3cc29e8bea4d7b935fecdccd2
We have migrated to flake8 and most distros don't have the version of
pep8 that flake8 (and hacking) use. Instead of installing pep8 from
packages it should be installed from pip
Change-Id: I86e4f8316f3cdc27303bfd039a78c0d6202ce321