tests/test-merge-subrepos.t

patchbomb: add a 'patchbomb.intro' option

This option allows the user to control the default behavior for
including an introduction message. This avoids having to tirelessly
skip the intro for people contributing to Mercurial.

The three possibles values are:
- always,
- auto (default, current behavior),
- never.

I was thinking of ("true", "false", "") (empty value being auto) but I ruled it
out as too confusing.

This new config option reuses the pre-existing 'patchbomb' section.

  $ 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]