tests/test-merge-subrepos.t

phase: attach phase to the transaction instead of the lock

The phase cache file is no longer written on lock release, it is now handled by
the transaction (as changesets and obsolescence markers are).

(Hooray)

As we stop relying on the lock to write phase, repos with no existing phase
information will need to wait for a phase move or a strip to happen in order to
get the first write in the `phaseroots` file. This explain the change in
test-inherit-mode.t.

This should not have any side effects but in very obscure cases where
people interact with pre-2.1 and post-2.1 versions of Mercurial on the
same repo while having MQ patches applied but the MQ extension
disabled from time to time. A case unlikely enough to not be worth
preserving the old behavior with awful hacks.

  $ hg init

  $ echo a > a
  $ hg ci -qAm 'add a'

  $ hg init subrepo
  $ echo 'subrepo = http://example.net/libfoo' > .hgsub
  $ hg ci -qAm 'added subrepo'

  $ hg up -qC 0
  $ echo ax > a
  $ hg ci -m 'changed a'
  created new head

  $ hg up -qC 1
  $ cd subrepo
  $ echo b > b
  $ hg add b
  $ cd ..

Should fail, since there are added files to subrepo:

  $ hg merge
  abort: uncommitted changes in subrepository 'subrepo'
  [255]