tests/test-diff-newlines.t

changegroup: replace changegroup with makechangegroup

As part of reducing the number of changegroup creation APIs, let's replace the
changegroup function with makechangegroup. This pushes the responsibility of
creating the outgoing set to the caller, but that seems like a simple and
reasonable concept for the caller to be aware of.

Differential Revision: https://phab.mercurial-scm.org/D668

  $ hg init

  $ $PYTHON -c 'open("a", "wb").write(b"confuse str.splitlines\nembedded\rnewline\n")'
  $ hg ci -Ama -d '1 0'
  adding a

  $ echo clean diff >> a
  $ hg ci -mb -d '2 0'

  $ hg diff -r0 -r1
  diff -r 107ba6f817b5 -r 310ce7989cdc a
  --- a/a	Thu Jan 01 00:00:01 1970 +0000
  +++ b/a	Thu Jan 01 00:00:02 1970 +0000
  @@ -1,2 +1,3 @@
   confuse str.splitlines
   embedded\r (no-eol) (esc)
  newline
  +clean diff