tests/test-revset-dirstate-parents.t

revlog: move the details of revlog "v2" index inside revlog.utils.constants

the revlog module is quite large and this kind of format information would handy
for other module. So let us start to gather this information about the format in
a more appropriate place.

We update various reference to this information to use the new "source of truth"
in the process.

Differential Revision: https://phab.mercurial-scm.org/D10305

  $ HGENCODING=utf-8
  $ export HGENCODING

  $ try() {
  >   hg debugrevspec --debug $@
  > }

  $ log() {
  >   hg log --template '{rev}\n' -r "$1"
  > }

  $ hg init repo
  $ cd repo

  $ try 'p1()'
  (func
    (symbol 'p1')
    None)
  * set:
  <baseset []>
  $ try 'p2()'
  (func
    (symbol 'p2')
    None)
  * set:
  <baseset []>
  $ try 'parents()'
  (func
    (symbol 'parents')
    None)
  * set:
  <baseset+ []>

null revision
  $ log 'p1()'
  $ log 'p2()'
  $ log 'parents()'

working dir with a single parent
  $ echo a > a
  $ hg ci -Aqm0
  $ log 'p1()'
  0
  $ log 'tag() and p1()'
  $ log 'p2()'
  $ log 'parents()'
  0
  $ log 'tag() and parents()'

merge in progress
  $ echo b > b
  $ hg ci -Aqm1
  $ hg up -q 0
  $ echo c > c
  $ hg ci -Aqm2
  $ hg merge -q
  $ log 'p1()'
  2
  $ log 'p2()'
  1
  $ log 'tag() and p2()'
  $ log 'parents()'
  1
  2

  $ cd ..