Backport #34370 by @GWDx
Issue: After switching the default branch, other branches are still
compared against the old default branch due to outdated divergence
cache.
Change: Clear the divergence cache in SetRepoDefaultBranch to ensure
correct comparisons against the new default branch.
Fixes#34369
Co-authored-by: GWDx <gwdx@mail.ustc.edu.cn>
Change all license headers to comply with REUSE specification.
Fix#16132
Co-authored-by: flynnnnnnnnnn <flynnnnnnnnnn@github>
Co-authored-by: John Olheiser <john.olheiser@gmail.com>
