tests/test-exchange-obsmarkers-case-A4.t

sshpeer: don't read from stderr when that behavior is disabled

We previously prevented the creation of doublepipe instances when
we're not supposed to automatically read from stderr. However,
there were other automatic calls to read from stderr that were
undermining this effort.

This commit prevents all automatic reads from stderr from occurring
when they are supposed to be disabled.

Because stderr is no longer being read, we need to call "readavailable"
from tests so stderr is read from.

Test output changes because stderr is now always (manually) read after
stdout. And, since sshpeer no longer automatically tends to stderr,
no "remote: " messages are printed. This should fix non-deterministic
test output.

FWIW, doublepipe automatically reads from stderr when reading from
stdout, so I'm not sure some of these calls to self._readerr() are
even needed.

Differential Revision: https://phab.mercurial-scm.org/D2571

============================================
Testing obsolescence markers push: Cases A.4
============================================

Mercurial pushes obsolescences markers relevant to the "pushed-set", the set of
all changesets that requested to be "in sync" after the push (even if they are
already on both side).

This test belongs to a series of tests checking such set is properly computed
and applied. this does not tests "obsmarkers" discovery capabilities.

Category A: simple cases
Testcase 4: Push in the middle of the obsolescence chain

A.4 Push in the middle of the obsolescence chain
================================================

.. (Where we show that we should not push the marker without the successors)
..
.. {{{
..   B ◔
..     |
..   A⇠ø⇠○ A'
..     |/
..     ● O
.. }}}
..
.. Markers exist from:
..
..  * `A ø⇠○ A'`
..  * chain from A
..
.. Command runs:
..
..  * hg push -r B
..
.. Expected exchange:
..
..  * Chain from A
..
.. Expected Exclude:
..
..  * `Ai ø⇠○ A'`

Setup
-----

  $ . $TESTDIR/testlib/exchange-obsmarker-util.sh

initial

  $ setuprepos A.4
  creating test repo for test case A.4
  - pulldest
  - main
  - pushdest
  cd into `main` and proceed with env setup
  $ cd main
  $ mkcommit A0
  $ mkcommit B
  $ hg update 0
  0 files updated, 0 files merged, 2 files removed, 0 files unresolved
  $ mkcommit A1
  created new head
  $ hg debugobsolete aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa `getid 'desc(A0)'`
  $ hg debugobsolete `getid 'desc(A0)'` `getid 'desc(A1)'`
  obsoleted 1 changesets
  1 new orphan changesets
  $ hg log -G --hidden
  @  e5ea8f9c7314 (draft): A1
  |
  | *  06055a7959d4 (draft): B
  | |
  | x  28b51eb45704 (draft): A0
  |/
  o  a9bdc8b26820 (public): O
  
  $ inspect_obsmarkers
  obsstore content
  ================
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 28b51eb45704506b5c603decd6bf7ac5e0f6a52f 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  28b51eb45704506b5c603decd6bf7ac5e0f6a52f e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  $ cd ..
  $ cd ..

Actual Test for first version
-----------------------------

  $ dotest A.4 B -f
  ## Running testcase A.4
  # testing echange of "B" (06055a7959d4)
  ## initial state
  # obstore: main
  28b51eb45704506b5c603decd6bf7ac5e0f6a52f e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 28b51eb45704506b5c603decd6bf7ac5e0f6a52f 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pushdest
  # obstore: pulldest
  ## pushing "B" from main to pushdest
  pushing to pushdest
  searching for changes
  remote: adding changesets
  remote: adding manifests
  remote: adding file changes
  remote: added 2 changesets with 2 changes to 2 files
  remote: 1 new obsolescence markers
  ## post push state
  # obstore: main
  28b51eb45704506b5c603decd6bf7ac5e0f6a52f e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 28b51eb45704506b5c603decd6bf7ac5e0f6a52f 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pushdest
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 28b51eb45704506b5c603decd6bf7ac5e0f6a52f 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pulldest
  ## pulling "06055a7959d4" from main into pulldest
  pulling from main
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 2 files
  1 new obsolescence markers
  new changesets 28b51eb45704:06055a7959d4
  (run 'hg update' to get a working copy)
  ## post pull state
  # obstore: main
  28b51eb45704506b5c603decd6bf7ac5e0f6a52f e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 28b51eb45704506b5c603decd6bf7ac5e0f6a52f 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pushdest
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 28b51eb45704506b5c603decd6bf7ac5e0f6a52f 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pulldest
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 28b51eb45704506b5c603decd6bf7ac5e0f6a52f 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}