tests/test-hgk.t

patch.diffopts: add support for noprefix

In an upcoming patch we'll enable support as an option to 'hg diff' as well.

The tests reflect the current state of the world -- as we add support we'll see
changes in the test output.

Minimal hgk check

  $ echo "[extensions]" >> $HGRCPATH
  $ echo "hgk=" >> $HGRCPATH
  $ hg init repo
  $ cd repo
  $ echo a > a
  $ hg ci -Am adda
  adding a
  $ hg debug-cat-file commit 0
  tree a0c8bcbbb45c
  parent 000000000000
  author test 0 0
  revision 0
  branch default
  phase draft
  
  adda

  $ cd ..