tests/test-revlog-packentry.t

run-tests: move t test parsing into its own function

Test parsing is somewhat complicated. This patch extracts it into its
own function.

The impetus of this patch is folding tsttest() into the TTest class.
Subsequent patches will continue this work until tsttest() no longer
exists.

  $ 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    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0       0  .....       0 b80de5d13875 000000000000 000000000000 (re)
       1         0      24  .....       1 0376abec49b8 000000000000 000000000000 (re)

  $ cd ..