tests/test-double-merge.t

context: make repo[<filtered binary nodeid>] match node

If you pass in a binary nodeid of a filtered node to repo.__getitem__,
it would run through this code:

    try:
        self._node = changeid
	self._rev = repo.changelog.rev(changeid)
	return
    except error.FilteredLookupError:
        raise
    except LookupError:
         pass

However, repo.changelog.rev() would raise a FilteredLookupError, not
FilteredRepoLookupError. Instead, we would hit the "except
LookupError" and continue, trying to interpret the nodeid as a
bookmark etc. The end result would be an error like this:

  abort: unknown revision 'ddadbd7c40ef8b8ad6d0d01a7a842092fc431798'!

After this patch, it would instead be:

  abort: 00changelog.i@ddadbd7c40ef8b8ad6d0d01a7a842092fc431798: filtered node!

This only happens when we get a binary nodeid, which means it's not
string directly from the user, so it would be a programming error if
it happened. It's therefore a little hard to test (I checked
test-context.py, but it doesn't use obsmarkers).

It looks like this has been wrong ever since dc25ed84bee8 (changectx:
issue a FilteredRepoLookupError when applicable, 2014-10-15).

Differential Revision: https://phab.mercurial-scm.org/D3144

  $ hg init repo
  $ cd repo

  $ echo line 1 > foo
  $ hg ci -qAm 'add foo'

copy foo to bar and change both files
  $ hg cp foo bar
  $ echo line 2-1 >> foo
  $ echo line 2-2 >> bar
  $ hg ci -m 'cp foo bar; change both'

in another branch, change foo in a way that doesn't conflict with
the other changes
  $ hg up -qC 0
  $ echo line 0 > foo
  $ hg cat foo >> foo
  $ hg ci -m 'change foo'
  created new head

we get conflicts that shouldn't be there
  $ hg merge -P
  changeset:   1:484bf6903104
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     cp foo bar; change both
  
  $ hg merge --debug
    searching for copies back to rev 1
    unmatched files in other:
     bar
    all copies found (* = to merge, ! = divergent, % = renamed and deleted):
     src: 'foo' -> dst: 'bar' *
    checking for directory renames
  resolving manifests
   branchmerge: True, force: False, partial: False
   ancestor: e6dc8efe11cc, local: 6a0df1dad128+, remote: 484bf6903104
   preserving foo for resolve of bar
   preserving foo for resolve of foo
  starting 4 threads for background file closing (?)
   bar: remote copied from foo -> m (premerge)
  picked tool ':merge' for bar (binary False symlink False changedelete False)
  merging foo and bar to bar
  my bar@6a0df1dad128+ other bar@484bf6903104 ancestor foo@e6dc8efe11cc
   premerge successful
   foo: versions differ -> m (premerge)
  picked tool ':merge' for foo (binary False symlink False changedelete False)
  merging foo
  my foo@6a0df1dad128+ other foo@484bf6903104 ancestor foo@e6dc8efe11cc
   premerge successful
  0 files updated, 2 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

contents of foo
  $ cat foo
  line 0
  line 1
  line 2-1

contents of bar
  $ cat bar
  line 0
  line 1
  line 2-2

  $ cd ..