[PATCH 1 of 2] merge: use labels in prompts to the user

[timeless]

Simon Farnsworth wrote:
> diff --git a/tests/failfilemerge.py b/tests/failfilemerge.py
> --- a/tests/failfilemerge.py
> +++ b/tests/failfilemerge.py
> @@ -9,7 +9,7 @@
>  )
>
>  def failfilemerge(filemergefn,
> -        premerge, repo, mynode, orig, fcd, fco, fca, labels=None):
> +                  premerge, repo, mynode, orig, fcd, fco, fca, labels=None):
>      raise error.Abort("^C")
>      return filemergefn(premerge, repo, mynode, orig, fcd, fco, fca, labels)
>

This is unrelated cleanup that should probably be in a different
commit (just to make things easier for anyone reading the big commit).