tests/test-hgk.t

manifest: disallow setting the node id of an entry to None

manifest.diff() uses None as a special value to denote the absence of
a file, so setting a file node to None means you then can't trust
manifest.diff().

This should also make future manifest work slightly easier.

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 ..