tests/test-backwards-remove.t

transaction-summary: display the summary for all transactions

Now that we records "all" changes happening in a transaction (in tr.changes)
we will be able to provide better report on various changes (phases turned
public, changeset obsoleted, branch merged or created, etc..)

This is far too late in the cycle to play with this, but having this existing
method called more widely will help extensions to play around with various
options during the 4.4 cycle.

Instead of calling registersummarycallback only for transactions we want, we
always call it and use the transaction name to decide when to report (eg: we
do not want `hg amend` to report new obsoleted changesets). Filtering on
transaction name does not seems great, but seems good enough for the moment.
We can change the API during the next cycle.

The previous manual call during unbundling of the bundle2 "obsmarkers" part is
no longer necessary and has been dropped.

  $ hg init
  $ echo This is file a1 > a
  $ hg add a
  $ hg commit -m "commit #0"
  $ ls
  a
  $ echo This is file b1 > b
  $ hg add b
  $ hg commit -m "commit #1"
  $ hg co 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved

B should disappear

  $ ls
  a