tests/test-merge4.t

logtoprocess: drop support for ui.log() call with invalid msg arguments (BC)

Before, the logtoprocess extension put a formatted message into $MSG1, and
its arguments to $MSG2... If the specified arguments couldn't be formatted
because of a caller bug, an unformatted message was passed in to $MSG1
instead of exploding. This behavior doesn't make sense.

Since I'm planning to formalize the ui.log() interface such that we'll no
longer have to extend the ui class, I want to remove any features not
conforming to the ui.log() API. So this patch removes the support for
ill-formed arguments, and $MSG{n} (where n > 1) parameters which seems
useless as long as the message can be formatted. The $MSG1 variable isn't
renamed for the maximum compatibility.

In future patches, a formatted msg will be passed to a processlogger object,
instead of overriding the ui.log() function.

.. bc::

   The logtoprocess extension no longer supports invalid ``ui.log()``
   arguments. A log message is always formatted and passed in to the
   ``$MSG1`` environment variable.

  $ hg init
  $ echo This is file a1 > a
  $ hg add a
  $ hg commit -m "commit #0"
  $ echo This is file b1 > b
  $ hg add b
  $ hg commit -m "commit #1"
  $ hg update 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo This is file c1 > c
  $ hg add c
  $ hg commit -m "commit #2"
  created new head
  $ hg merge 1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ rm b
  $ echo This is file c22 > c

Test hg behaves when committing with a missing file added by a merge

  $ hg commit -m "commit #3"
  abort: cannot commit merge with missing files
  [255]