tests/test-merge-subrepos.t

manifest: use 't' for tree manifest flag

We currently use 'd' to indicate that a manifest entry is a
directory. Let's switch to 't', since that's not a valid hex digit and
therefore easier to spot in the raw manifest data.

This will break any existing repos with tree manifests, but it's still
an experimental feature and there are probably only a few test repos
in existence with 'd' flags.

  $ 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]