tests/test-hgk.t

branch: operate on branch names in local string space where possible

Previously, branch names were ideally manipulated as UTF-8 strings,
because they were stored as UTF-8 in the dirstate and the changelog
and could not be safely converted to the local encoding and back.

However, only about 80% of branch name code was actually using the
right encoding conventions. This patch uses the localstr addition to
allow working on branch names as local strings, which simplifies
handling so that the previously incorrect code becomes correct.

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