tests/test-push-checkheads-pruned-B5.t

wireprotov2: client support for following content redirects

And with the server actually sending content redirects, it is finally
time to implement client support for following them!

When a redirect response is seen, we wait until all data for that
request has been received (it should be nearly immediate since no
data is expected to follow the redirect message). Then we use
a URL opener to make a request. We stuff that response into the
client handler and construct a new response object to track it.

When readdata() is called for servicing requests, we attempt to
read data from the first redirected response. During data reading,
data is processed similarly to as if it came from a frame payload.

The existing test for the functionality demonstrates the client
transparently following the redirect and obtaining the command
response data from an alternate URL!

There is still plenty of work to do here, including shoring up
testing. I'm not convinced things will work in the presence of
multiple redirect responses. And we don't yet implement support
for integrity verification or configuring server certificates
to validate the connection. But it's a start. And it should enable
us to start experimenting with "real" caches.

Differential Revision: https://phab.mercurial-scm.org/D4778

====================================
Testing head checking code: Case B-5
====================================

Mercurial checks for the introduction of new heads on push. Evolution comes
into play to detect if existing branches on the server are being replaced by
some of the new one we push.

This case is part of a series of tests checking this behavior.

Category B: simple case involving pruned changesets
TestCase 5: multi-changeset branch, mix of pruned and superceeded

.. old-state:
..
.. * 3 changeset branch
..
.. new-state:
..
.. * old head is pruned
.. * old mid is superceeded
.. * old root is pruned
..
.. expected-result:
..
.. * push allowed
..
.. graph-summary:
..
..   B ⊗
..     |
..   A ø⇠◔ A'
..     | |
..   B ⊗ |
..     |/
..     ●

  $ . $TESTDIR/testlib/push-checkheads-util.sh

Test setup
----------

  $ mkdir B5
  $ cd B5
  $ setuprepos
  creating basic server and client repo
  updating to branch default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd server
  $ mkcommit B0
  $ mkcommit C0
  $ cd ../client
  $ hg pull
  pulling from $TESTTMP/B5/server
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 2 files
  new changesets d73caddc5533:821fb21d0dd2 (2 drafts)
  (run 'hg update' to get a working copy)
  $ hg up 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ mkcommit B1
  created new head
  $ hg debugobsolete --record-parents `getid "desc(A0)"`
  obsoleted 1 changesets
  2 new orphan changesets
  $ hg debugobsolete `getid "desc(B0)"` `getid "desc(B1)"`
  obsoleted 1 changesets
  $ hg debugobsolete --record-parents `getid "desc(C0)"`
  obsoleted 1 changesets
  $ hg log -G --hidden
  @  25c56d33e4c4 (draft): B1
  |
  | x  821fb21d0dd2 (draft): C0
  | |
  | x  d73caddc5533 (draft): B0
  | |
  | x  8aaa48160adc (draft): A0
  |/
  o  1e4be0697311 (public): root
  

Actual testing
--------------

  $ hg push
  pushing to $TESTTMP/B5/server
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)
  3 new obsolescence markers
  obsoleted 3 changesets

  $ cd ../..