Fix remote cache miss

[jheaff1]

In some cases, the hermetic python toolchain would generate .pyc files
when being used, resulting in a remote cache miss. This commit excludes
generated files from the "files" filegroup to resolve this issue

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 (please, look at the "Scope of the project" section in the README.md file)
• 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?

Issue Number: N/A

What is the new behavior?

Does this PR introduce a breaking change?

• Yes
• No

Other information

[hrfuller]

LGTM. Could you please clarify when the pyc's are generated. Is it during some build step of the hermetic interpreter external repo?

[f0rmiga]

Please, see: #713.

[jheaff1]

After reading #713, it seems that the issue shouldn’t occur if not building as root. I was indeed building as the root user “ContainerAdministrator” within a Windows Container. I’ll try building as non-root. Thanks!

[f0rmiga]

Cool! I'm working on a solution to warn the user about this.

[f0rmiga]

@jheaff1 I created #749. I'll add the same functionality under Windows next.

[jheaff1]

@f0rmiga This issue does indeed go away when building as non-root, however when building as non-root in a Windows Container, symlinks cannot be created, which prevents the usage of features like --enable_runfiles (See here), which is used in rules_python in fact:

rules_python/.bazelrc

Lines 19 to 22 in aef17ad

	# Windows makes use of runfiles for some rules
	build --enable_runfiles
	# TODO(f0rmiga): remove this so that other features don't start relying on it.
	startup --windows_enable_symlinks

Given this scenario, and perhaps others where it is troublesome to build as non-root, should we instead exclude the pyc files from the filegroup?

[f0rmiga]

Then, I guess we should exclude unconditionally under Windows only. Thanks for the extra info on Windows!

[f0rmiga]

Another thing we can add is an attribute to exclude them under Linux too.