We have several tox environments that don't really share the same
dependencies. Currently we put everything into test-requirements.txt,
meaning the linter environment gets testinfra and testinfra
environment gets things like ansible-lint it's not using.
Apart from being a bit faster not installing things, this is helpful
for restoring the ansible -devel test. In that case, we have ansible
as a project dependency; when installing from git, ansible now
installs itself as "ansible-base" ("ansible" is the released pypi
package that incorporates collections). So if we install ansible-lint
in the testinfra environment, this pulls in ansible ... and then it
breaks when tox wants to install our Zuul clone of upstream ansible
(you can't have ansible and ansible-base together).
Change-Id: I5f3fc93e6ddd611f319fa269e122ed576c9cb378
001ad4d7b1