tests/test-custom-filters.t

discovery: change users of `outgoing.missingheads` to `outgoing.ancestorsof`

The attribute `missingheads` was recently renamed to `ancestorsof`, as it,
despite the old name, doesn’t contain the missing heads but the changesets that
were requested (including ancestors) for the outgoing operation.

Changing all the users enables to print a warning if the old name is used.

There is a good chance that some of the users are buggy because of the old name.
Changing them to use the new name makes it more obvious that they are buggy. All
users need to be reviewed for bugs. When sending patches for fixing them, the
change will be more obvious without having to explain again and again the
discrepancy of the old attribute name and what it actually contained.

  $ hg init

  $ cat > .hg/hgrc <<EOF
  > [extensions]
  > prefixfilter = prefix.py
  > [encode]
  > *.txt = stripprefix: Copyright 2046, The Masters
  > [decode]
  > *.txt = insertprefix: Copyright 2046, The Masters
  > EOF

  $ cat > prefix.py <<EOF
  > from mercurial import error
  > def stripprefix(s, cmd, filename, **kwargs):
  >     header = b'%s\n' % cmd
  >     if s[:len(header)] != header:
  >         raise error.Abort(b'missing header "%s" in %s' % (cmd, filename))
  >     return s[len(header):]
  > def insertprefix(s, cmd):
  >     return b'%s\n%s' % (cmd, s)
  > def reposetup(ui, repo):
  >     repo.adddatafilter(b'stripprefix:', stripprefix)
  >     repo.adddatafilter(b'insertprefix:', insertprefix)
  > EOF

  $ cat > .hgignore <<EOF
  > .hgignore
  > prefix.py
  > prefix.pyc
  > __pycache__/
  > EOF

  $ cat > stuff.txt <<EOF
  > Copyright 2046, The Masters
  > Some stuff to ponder very carefully.
  > EOF
  $ hg add stuff.txt
  $ hg ci -m stuff

Repository data:

  $ hg cat stuff.txt
  Some stuff to ponder very carefully.

Fresh checkout:

  $ rm stuff.txt
  $ hg up -C
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat stuff.txt
  Copyright 2046, The Masters
  Some stuff to ponder very carefully.
  $ echo "Very very carefully." >> stuff.txt
  $ hg stat
  M stuff.txt

  $ echo "Unauthorized material subject to destruction." > morestuff.txt

Problem encoding:

  $ hg add morestuff.txt
  $ hg ci -m morestuff
  abort: missing header "Copyright 2046, The Masters" in morestuff.txt
  [255]
  $ hg stat
  M stuff.txt
  A morestuff.txt