[WIP] add ahead/behind commit count for branches. Something is currently broken here.

  console.log(flatFilesData.filter(entry => entry.file.includes('njk')))

    branches.forEach((branch) => {
      const branchDescription = branchesToAdd.find(branchToAdd => branchToAdd.name === branch.name)
      const compareTo = branchDescription.compareTo || reposConfig.repos[repoName].defaultBranch
      const compareToBranch = branches.find((test) => test.name = compareTo)

      const compareToBranchCommits = new Set()
      let currentCommit = commits.get(compareToBranch.head)
      while (currentCommit !== undefined) {
        compareToBranchCommits.add(currentCommit.hash)
        currentCommit = commits.get(currentCommit.parent)
      }

      const thisBranchCommits = new Set()
      currentCommit = commits.get(branch.head)
      while (currentCommit !== undefined) {
        thisBranchCommits.add(currentCommit.hash)
        currentCommit = commits.get(currentCommit.parent)
      }

      // At this point, we have all commits in the compareTo branch in one set, and
      // all commits from this branch in another set.
      const onlyInThisBranch = thisBranchCommits.difference(compareToBranchCommits).size
      const onlyInCompareToBranch = compareToBranchCommits.difference(thisBranchCommits).size
      
      branch['ahead'] = onlyInThisBranch
      branch['behind'] = onlyInCompareToBranch
      branch['compareTo'] = compareTo
    })

  if (branchName === 'main') {
    console.log(files)
  }

    "lib": ["esnext", "dom"],