tests/test-narrow-copies.t

copies: filter out copies from non-existent source later in _chain()

_changesetforwardcopies() repeatedly calls _chain(). That is very
expensive because _chain() does lookups in the manifest. I hope to
split up the function in two parts: 1) simple chaining, not
considering end points, and 2) filter out files that don't exist in
the end points (and ping-pong copies/renames).

This patches gets us closer to that by moving the check for
non-existent source later in the function. Now there are no more
checks for "src" and "dst" in the first loop; all the filtering of
invalid copies is done in the second loop. The code also looks much
more consistent now.

No measureable impact on `hg debugpathcopies 4.0 4.8`. That shouldn't
be surprising since the only case we're doing more checks now is in
case of chained copies/renames, which are quire rare in practice.

Differential Revision: https://phab.mercurial-scm.org/D6277

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

create full repo

  $ hg init master
  $ cd master

  $ mkdir inside
  $ echo inside > inside/f1
  $ mkdir outside
  $ echo outside > outside/f2
  $ hg ci -Aqm 'initial'

  $ hg mv outside/f2 inside/f2
  $ hg ci -qm 'move f2 from outside'

  $ echo modified > inside/f2
  $ hg ci -qm 'modify inside/f2'

  $ mkdir outside
  $ echo new > outside/f3
  $ hg ci -Aqm 'add outside/f3'
  $ cd ..

  $ hg clone --narrow ssh://user@dummy/master narrow --include inside -r 2
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 3 changes to 2 files
  new changesets *:* (glob)
  updating to branch default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd narrow

  $ hg co 'desc("move f2")'
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg status
  $ hg diff
  $ hg diff --change . --git
  diff --git a/inside/f2 b/inside/f2
  new file mode 100644
  --- /dev/null
  +++ b/inside/f2
  @@ -0,0 +1,1 @@
  +outside

  $ hg log --follow inside/f2 -r tip
  changeset:   2:bcfb756e0ca9
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     modify inside/f2
  
  changeset:   1:5a016133b2bb
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     move f2 from outside
  
  $ echo new > inside/f4
  $ hg ci -Aqm 'add inside/f4'
  $ hg pull -q
  $ hg --config extensions.rebase= rebase -d tip
  rebasing 3:4f84b666728c "add inside/f4"
  saved backup bundle to $TESTTMP/narrow/.hg/strip-backup/4f84b666728c-4269b76e-rebase.hg

  $ hg co -q 0
  $ echo modified > inside/f1
  $ hg ci -qm 'modify inside/f1'
  $ echo new > inside/f5
  $ hg ci -Aqm 'add inside/f5'
  $ hg --config extensions.rebase= rebase -d 'public()' -r .
  rebasing 6:610b60178c28 "add inside/f5" (tip)
  saved backup bundle to $TESTTMP/narrow/.hg/strip-backup/610b60178c28-65716a78-rebase.hg