anchor.diff:      member this.FetchFile (repository : String) (commit : Revision) (path : String) = async {
         let gitDir = repository
         let command =
  -        "git --git-dir=" + gitDir +
  +        "git -C " + gitDir +
           " show " + commit + ":" + path
         return! runBash(command)
       }
  
positive.code:   member this.LocalTags (repository : String) = async {
      let gitDir = repository
      let command =
        "--no-pager --git-dir=" + gitDir +
        " tag"
      let! output = runBash(command)
  
  
negative.code:     member this.FetchCommit (repository : String) (commit : Revision) = async {
        let gitDir = repository
        let command =
          "git -C " + gitDir +
          " fetch origin " + commit
        do!
          runBash(command)
  