anchor.diff:  /// This version doesn't throw an exception if an error occurs. It just traces the error.
   let showGitCommand repositoryDir command =
       let ok,msg,errors = runGitCommand repositoryDir command
  -    msg |> Seq.iter (tracefn "%s")
  +    msg |> Seq.iter (logfn "%s")
       if errors <> "" then
         traceError <| sprintf "Errors: %s" errors
   
  
positive.code:         let ok,msg,errors = runGitCommand repositoryDir command
          if msg.Count = 0 then "" else
          try
              msg |> Seq.iter (tracefn "%s")
              msg.[0]
          with 
          | exn -> failwithf "Git didn't return a msg.\r\n%s" errors
  
negative.code:     let ok,msg,error = runGitCommand repositoryDir command
  
      if not ok then failwith error else 
      msg |> Seq.iter (logfn "%s")
  
  /// [omit]
  let gitCommandf repositoryDir fmt = Printf.ksprintf (gitCommand repositoryDir) fmt
  