tests/test-remotefilelog-blame.t

changing-files: rework the way we store changed files in side-data

We need to store new data so this is a good opportunity to rework this fully.

1) We directly store the list of affected file in the side data:

* This avoid having to fetch and parse the `files` list in the revision in
  addition to the sidedata. Making the data more self sufficient.

* This work around situation where that `files` field contains wrong
  information, and open the way to other bug fixing (eg: issue6219)

* The format (fixed initial index, sorted files) allow for fast lookup of
  filename within the structure.

* This unify the storage of affected files and copies sources and destination,
  limiting the number filename stored redundantly.

* This prepare for the fact we should drop the `files` as soon as we do any
  change affecting the revision schema.

* This rely on compression to avoid a significant increase of the changelog.d.
  More testing on this will be done before we freeze the final format.


2) We can store additional data:

* The new "merged" field,

* A future "salvaged" set recording files that might have been deleted but have
  were still present in the final result.

Differential Revision: https://phab.mercurial-scm.org/D9090

#require no-windows

  $ . "$TESTDIR/remotefilelog-library.sh"

  $ hg init master
  $ cd master
  $ cat >> .hg/hgrc <<EOF
  > [remotefilelog]
  > server=True
  > EOF
  $ echo x > x
  $ hg commit -qAm x
  $ echo y >> x
  $ hg commit -qAm y
  $ echo z >> x
  $ hg commit -qAm z
  $ echo a > a
  $ hg commit -qAm a

  $ cd ..

  $ hgcloneshallow ssh://user@dummy/master shallow -q
  2 files fetched over 1 fetches - (2 misses, 0.00% hit ratio) over *s (glob)
  $ cd shallow

Test blame

  $ hg blame x
  0: x
  1: y
  2: z
  2 files fetched over 1 fetches - (2 misses, 0.00% hit ratio) over *s (glob)

Test grepping the working directory.

  $ hg grep --all-files x
  x:x
  $ echo foo >> x
  $ hg grep --all-files x
  x:x