tests/test-histedit-outgoing.t

commit: improve the files field of changelog for merges

Currently, the files list of merge commits repeats all the deletions
(either actual deletions, or files that got renamed) that happened
between base and p2 of the merge. If p2 is the main branch, the list
can easily be much bigger than the change being merged.

This results in various problems worth improving:
- changelog is bigger than necessary
- `hg log directory` lists many unrelated merge commits, and `hg log
  -v -r commit` frequently fills multiple screens worth of files
- it possibly slows down adjustlinkrev, by forcing it to read more
  manifests, and that function can certainly be a bottleneck
- the server side of pulls can waste a lot of time simply opening the
  filelogs for pointless files (the constant factors for opening even
  a tiny filelog is apparently pretty bad)

So stop listing such files as described in the code.  Impacted merge
commits and their descendants get a different hash than they would
have without this. This doesn't seem problematic, except for
convert. The previous commit helped with that in the hg->hg case (but
if you do svn->hg twice from scratch, hashes can still change).

The rest of the description is numbers. I don't have much to report,
because recreating the files list of existing repositories is not
easy:
- debugupgradeformat and bundle/unbundle don't recreate the list
- export/import tends to choke quickly applying patches or on
  description that contain diffs,
- merge commits from the convert extension don't have the right files
  list for reasons orthogonal to the current commit
- replaying the merge with hg update/hg merge/hg revert --all/hg
  commit can end up failing in hg revert
- I wasn't sure that using debugsetparents + debugrebuilddirstate
  would really build the right thing

I measured commit time before and after this change, in a case with no
files filtered out, several files filtered out (no difference) and 5k
files filtered out (+1% time).

Recreating the 100 more recent merges in a private repo, the
concatenated uncompressed files lists goes from 1.12MB to
0.52MB. Excluding 3 merges that are not representative, then the size
goes from 570k to 15k.
I converted part of mozilla-central, and observed file list shrinking
quite a bit too, starting at the very first merge, 733641d9feaf, going
from 550 files to 10 files (although they have relatively few merges,
so they probably wouldn't care).

Differential Revision: https://phab.mercurial-scm.org/D6613

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > histedit=
  > EOF

  $ initrepos ()
  > {
  >     hg init r
  >     cd r
  >     for x in a b c ; do
  >         echo $x > $x
  >         hg add $x
  >         hg ci -m $x
  >     done
  >     cd ..
  >     hg clone r r2 | grep -v updating
  >     cd r2
  >     for x in d e f ; do
  >         echo $x > $x
  >         hg add $x
  >         hg ci -m $x
  >     done
  >     cd ..
  >     hg init r3
  >     cd r3
  >     for x in g h i ; do
  >         echo $x > $x
  >         hg add $x
  >         hg ci -m $x
  >     done
  >     cd ..
  > }

  $ initrepos
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved

show the edit commands offered by outgoing
  $ cd r2
  $ HGEDITOR=cat hg histedit --outgoing ../r | grep -v comparing | grep -v searching
  pick 055a42cdd887 3 d
  pick e860deea161a 4 e
  pick 652413bf663e 5 f
  
  # Edit history between 055a42cdd887 and 652413bf663e
  #
  # Commits are listed from least to most recent
  #
  # You can reorder changesets by reordering the lines
  #
  # Commands:
  #
  #  e, edit = use commit, but stop for amending
  #  m, mess = edit commit message without changing commit content
  #  p, pick = use commit
  #  b, base = checkout changeset and apply further changesets from there
  #  d, drop = remove commit from history
  #  f, fold = use commit, but combine it with the one above
  #  r, roll = like fold, but discard this commit's description and date
  #
  $ cd ..

show the error from unrelated repos
  $ cd r3
  $ HGEDITOR=cat hg histedit --outgoing ../r | grep -v comparing | grep -v searching
  abort: repository is unrelated
  [1]
  $ cd ..

show the error from unrelated repos
  $ cd r3
  $ HGEDITOR=cat hg histedit --force --outgoing ../r
  comparing with ../r
  searching for changes
  warning: repository is unrelated
  pick 2a4042b45417 0 g
  pick 68c46b4927ce 1 h
  pick 51281e65ba79 2 i
  
  # Edit history between 2a4042b45417 and 51281e65ba79
  #
  # Commits are listed from least to most recent
  #
  # You can reorder changesets by reordering the lines
  #
  # Commands:
  #
  #  e, edit = use commit, but stop for amending
  #  m, mess = edit commit message without changing commit content
  #  p, pick = use commit
  #  b, base = checkout changeset and apply further changesets from there
  #  d, drop = remove commit from history
  #  f, fold = use commit, but combine it with the one above
  #  r, roll = like fold, but discard this commit's description and date
  #
  $ cd ..

test sensitivity to branch in URL:

  $ cd r2
  $ hg -q update 2
  $ hg -q branch foo
  $ hg commit -m 'create foo branch'
  $ HGEDITOR=cat hg histedit --outgoing '../r#foo' | grep -v comparing | grep -v searching
  pick f26599ee3441 6 create foo branch
  
  # Edit history between f26599ee3441 and f26599ee3441
  #
  # Commits are listed from least to most recent
  #
  # You can reorder changesets by reordering the lines
  #
  # Commands:
  #
  #  e, edit = use commit, but stop for amending
  #  m, mess = edit commit message without changing commit content
  #  p, pick = use commit
  #  b, base = checkout changeset and apply further changesets from there
  #  d, drop = remove commit from history
  #  f, fold = use commit, but combine it with the one above
  #  r, roll = like fold, but discard this commit's description and date
  #

test to check number of roots in outgoing revisions

  $ hg -q outgoing -G --template '{node|short}({branch})' '../r'
  @  f26599ee3441(foo)
  
  o  652413bf663e(default)
  |
  o  e860deea161a(default)
  |
  o  055a42cdd887(default)
  
  $ HGEDITOR=cat hg -q histedit --outgoing '../r'
  abort: there are ambiguous outgoing revisions
  (see 'hg help histedit' for more detail)
  [255]

  $ hg -q update -C 2
  $ echo aa >> a
  $ hg -q commit -m 'another head on default'
  $ hg -q outgoing -G --template '{node|short}({branch})' '../r#default'
  @  3879dc049647(default)
  
  o  652413bf663e(default)
  |
  o  e860deea161a(default)
  |
  o  055a42cdd887(default)
  
  $ HGEDITOR=cat hg -q histedit --outgoing '../r#default'
  abort: there are ambiguous outgoing revisions
  (see 'hg help histedit' for more detail)
  [255]

  $ cd ..