Function map_promotion_batch_evidence 

pub fn map_promotion_batch_evidence(
    repo: &str,
    base_tag: &str,
    head_tag: &str,
    commits: &[CompareCommit],
    commit_pulls: &[GitHubCommitPullAssociation],
) -> PromotionBatch

Converts a GitHub tag comparison into a platform-neutral PromotionBatch.