tests/test-issue1306.t

wireprotov2: move response handling out of httppeer

And fix some bugs while we're here.

The code for processing response data from the unified framing
protocol is mostly peer agnostic. The peer-specific bits are the
configuration of the client reactor and how I/O is performed. I
initially implemented things in httppeer for expediency.

This commit establishes a module for holding the peer API level
code for the framing based protocol. Inside this module we have
a class to help coordinate higher-level activities, such as managing
response object.

The client handler bits could be rolled into clientreactor. However,
I want clientreactor to be sans I/O and I want it to only be
concerned with protocol-level details, not higher-level concepts
like how protocol events are converted into peer API concepts. I
want clientreactor to receive a frame and then tell the caller what
should probably be done about it. If we start putting things like
future resolution into clientreactor, we'll constrain how the protocol
can be used (e.g. by requiring futures).

The new code is loosely based on what was in httppeer before. I
changed things a bit around response handling. We now buffer the
entire response "body" and then handle it as one atomic unit. This
fixed a bug around decoding CBOR data that spanned multiple frames.
I also fixed an off-by-one bug where we failed to read a single byte
CBOR value at the end of the stream. That's why tests have changed.

The new state of httppeer is much cleaner. It is largely agnostic
about framing protocol implementation details. That's how it should
be: the framing protocol is designed to be largely transport
agnostic. We want peers merely putting bytes on the wire and telling
the framing protocol where to read response data from.

There's still a bit of work to be done here, especially for
representing responses. But at least we're a step closer to having a
higher-level peer interface that can be plugged into the SSH peer
someday.

I initially added this class to wireprotoframing. However, we'll
eventually need version 2 specific functions to convert CBOR responses
into data structures expected by the code calling commands. This
needs to live somewhere. Since that code would be shared across peers,
we need a common module. We have wireprotov1peer for the equivalent
version 1 code. So I decided to establish wireprotov2peer.

Differential Revision: https://phab.mercurial-scm.org/D3379

https://bz.mercurial-scm.org/1306

Initialize remote repo with branches:

  $ hg init remote
  $ cd remote

  $ echo a > a
  $ hg ci -Ama
  adding a

  $ hg branch br
  marked working directory as branch br
  (branches are permanent and global, did you want a bookmark?)
  $ hg ci -Amb

  $ echo c > c
  $ hg ci -Amc
  adding c

  $ hg log
  changeset:   2:ae3d9c30ec50
  branch:      br
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     c
  
  changeset:   1:3f7f930ca414
  branch:      br
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     b
  
  changeset:   0:cb9a9f314b8b
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     a
  

  $ cd ..

Try cloning -r branch:

  $ hg clone -rbr remote local1
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 2 changes to 2 files
  new changesets cb9a9f314b8b:ae3d9c30ec50
  updating to branch br
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg -R local1 parents
  changeset:   2:ae3d9c30ec50
  branch:      br
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     c
  

Try cloning -rother clone#branch:

  $ hg clone -r0 remote#br local2
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 2 changes to 2 files
  new changesets cb9a9f314b8b:ae3d9c30ec50
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg -R local2 parents
  changeset:   0:cb9a9f314b8b
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     a
  

Try cloning -r1 clone#branch:

  $ hg clone -r1 remote#br local3
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 2 changes to 2 files
  new changesets cb9a9f314b8b:ae3d9c30ec50
  updating to branch br
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg -R local3 parents
  changeset:   1:3f7f930ca414
  branch:      br
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     b