fix: fetchcommits and terminates expnential deepening if no commits fetched (#330)

Author: nikhedonia

buckaroo/DefaultSourceExplorer.fs

@@ -101,7 +101,7 @@ type DefaultSourceExplorer (console : ConsoleManager, downloadManager : Download
     match maybeBranchRef with
     | Some branchRef ->
       yield branchRef.Revision
-      yield! gitManager.FetchCommits url branchRef.Revision
+      yield! gitManager.FetchCommits url branchRef.Name
       ()
     | None -> ()
   }

buckaroo/GitCli.fs

@@ -222,6 +222,7 @@ type GitCli (console : ConsoleManager) =
                 return (skip + (nextList |> List.length), nextList, fetchNext)
               })
               ( 0, List.empty, async { return () } )
+          |> AsyncSeq.takeWhile (fun (_, revs, _) -> revs.Length > 0)
           |> AsyncSeq.collect (fun (_, revs, fetchNext) -> asyncSeq {
             yield! revs |> AsyncSeq.ofSeq
             do! fetchNext