Fixed issue #648 for Python

[grepwood]

PR Checklist

Please check if your PR fulfills the following requirements:

• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• Other... Please describe:

What is the current behavior?

I have a couple targets at work that indirectly call py_binary and py3_binary respectively via py_image and py3_image. Without this change, these targets trigger errors on Bazel newer than when such unions were disallowed.

Issue Number: 648

What is the new behavior?

It works.

Does this PR introduce a breaking change?

• Yes
• No

Other information

Kinda funny this issue was fixed in 2019 for all the languages but Python :) I was quite confused since we're upgrading from 0.15.0 and this got merged in 0.7.0... well now I know why that was an issue. Here's a PR that should put this issue finally to rest.

[google-cla]

Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

View this failed invocation of the CLA check for more information.

For the most up to date status, view the checks section at the bottom of the pull request.

[linzhp]

Can you fix the CI issues?

[grepwood]

@linzhp I'm afraid there's an issue. I have this account registered for an email address different than what I normally use with Google services. What can we do to resolve this?

[github-actions]

This Pull Request has been automatically marked as stale because it has not had any activity for 180 days. It will be closed if no further activity occurs in 30 days.
Collaborators can add an assignee to keep this open indefinitely. Thanks for your contributions to rules_docker!