tests/test-revlog-packentry.t

simplemerge: take arguments as annotated context objects

The labels we put in conflict markers are formatted so the part before
the ':' (typically says things like "local") is padded so the ':' is
aligned among the labels. That means that if you specify a long label
for "base" but the conflict marker style is "merge" (i.e. 2-way), the
other two will have unwanted padding. We often don't specify a label
for the base, so we don't notice the problem (and it may very well be
that it didn't exist before my D11972).

I think the best fix is to pass the labels along with the context
objects, so the low-level code that switches on the marker style to
use (i.e. `simplemerge`) can do the formatting. This patch starts
doing that by passing a fully-formatted label to `simplemerge`. A
coming patch will move the formatting to `simplemerge`.

Differential Revision: https://phab.mercurial-scm.org/D12013

  $ hg init repo
  $ cd repo

  $ touch foo
  $ hg ci -Am 'add foo'
  adding foo

  $ hg up -C null
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved

this should be stored as a delta against rev 0

  $ echo foo bar baz > foo
  $ hg ci -Am 'add foo again'
  adding foo
  created new head

  $ hg debugindex foo
     rev linkrev nodeid       p1           p2
       0       0 b80de5d13875 000000000000 000000000000
       1       1 0376abec49b8 000000000000 000000000000

  $ cd ..