Description of the problem / feature request:

Currently --repo_env is not a common argument. I don't see how it could be useful if I just set it on build: If I first do bazel build it applies the repo_env and downloads the repository data. But if I then do bazel query repo_env is no longer applied, the repository cache is invalidated and all the repository data is downloaded again.

If I could just set --repo_env on common this would not happen.