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

  // FILE.TS
  const flatFilesData = flatFiles(reposData)
  console.log(flatFilesData.filter(entry => entry.file.includes('njk')))
  eleventyConfig.addTemplate(
    'repos/file.11ty.js',
    htmlPage(reposConfiguration, eleventyConfig, fileJsTemplate),

      }
      if (branch.description) { result['description'] = branch.description }
      if (branch.compareTo) { result['compareTo'] = branch.compareTo }

      return result
    }))

    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
    })

    cachedRepos.push({
      name: repoName,
      description: reposConfig.repos[repoName].description,

  const result = await exec(command)
  let files = result.stdout.split("\n").filter(item => item.length > 0 && item != ".")
  if (branchName === 'main') {
    console.log(files)
  }
  // TODO: this could be better. This is adding each sub-path of a file to a set, so that
  // we don't wind up with repeats, and then converting that back into an array. E.g. if
  // we have two files:

    "noImplicitAny": false,
    "module": "node18",
    "target": "es6",
    "lib": ["esnext", "dom"],
    "allowJs": true,
    "outDir": "dist"
  },