* Restrict to unit tests with devel (to be reverted later).
* Restrict lxml for Python 2.6.
* Revert "Restrict to unit tests with devel (to be reverted later)."
This reverts commit d0d87a8a0f.
(cherry picked from commit 935348ae78)
Co-authored-by: Felix Fontein <felix@fontein.de>
* Make sure ruamel.yaml.clib 0.2.2 is used for Python 2.7.
* Also add to unit tests requirements.
* Don't install on Python 2.6.
* Another constraints file.