tests/test-hgk.t

test-revert: add methodical revert with explicit file path

We now also test reverting file to the working directory parent
content. However this differs from the previously introduced test by using
the explicit path of each "case file" when calling revert. This should
result in the same result regarding file content and backup creation,
but the output of the `hg revert` call should differ.

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 ..