Release process broken when new requirement added

[laneb]

The release validation is run in a docker container based on the Dockerfile from the top of the release brannch. The Dockerfile currently installs the most recent SMV release for that release train, and the requirements are taken from that release. That means that the requirements that are installed in the image used for validation of the new release are the requirements of the old release. When new requirements are added - tox, for recent example - they're not installed in the image used for validation, and fail the tests if they're truly requirements.

[laneb]

Should be fixed now, but need to verify.