Overview

The Windows compile-required build fails in test_sync_repo_with_copybara.py while preparing the local Copybara source mirror.

Background

get_copybara_source_mirror_url() converts the Linux container path /tmp/copybara-output/source-mirror.git with Path.as_uri(). On Windows, Path interprets this POSIX path as a drive-less Windows path and raises ValueError: relative path can't be expressed as a file URI.

This failure is tracked by BF-45398.

Scope of Work

• buildscripts/copybara/sync_repo_with_copybara.py — construct the container-local file URI using POSIX path semantics.
• buildscripts/tests/test_sync_repo_with_copybara.py — add regression coverage for the expected URI.

Acceptance Criteria

• The Copybara source mirror URI is generated correctly on Windows.
• Existing Linux behavior remains unchanged.
• The unit test verifies file:///tmp/copybara-output/source-mirror.git.

Technical Notes

The fix uses PurePosixPath because the path is interpreted inside the Linux Copybara container, independent of the host operating system.