tests/test-hgk.t

check-code: fix issues with finding patterns in unified tests, fix tests

- old-style patterns without ^ were getting improperly anchored
- finditer was matching against beginning of line poorly
- \s was matching newlines
- [^x] was matching newlines

so we:

- remove earlier hacks for multiline matching
- fix unified test anchoring by adding .*
- replace \s with [ \t]
- replace [^x] with [^\nx]
- force all matches into multiline mode so ^ anchors work

This uncovers a number of test issues that are then repaired.

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
  committer test 0 0
  revision 0
  branch default
  
  adda