tests/test-eol-tag.t

match: teach diffmatcher.visitdir() to return 'all' if possible

This patch teaches differencematcher.visitdir() to return 'all' when
m1.visitdir() returns 'all' and m2 does not matches.

Before this patch, from a differencematcher.visitdir(), we always returned
either True or False. We never returned 'all' even when we can. This causes
problem when m1 and m2 of a differencematcher are themselves differencematcher.
In that case, we try to check:

`if self._m2_.visitdir(dir) == 'all'`

which will never be 'all' even though it can be.

This leads to iterating over a lot of sub-directory manifest, even though we
don't want to while extending a narrow clone. I am yet to measure the impact of
this but calculating manifest was taking ~50-60 seconds, so this should
definitely save some of time there.

Differential Revision: https://phab.mercurial-scm.org/D5814

https://bz.mercurial-scm.org/2493

Testing tagging with the EOL extension

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > eol =
  > 
  > [eol]
  > native = CRLF
  > EOF

setup repository

  $ hg init repo
  $ cd repo
  $ cat > .hgeol <<EOF
  > [patterns]
  > ** = native
  > EOF
  $ printf "first\r\nsecond\r\nthird\r\n" > a.txt
  $ hg commit --addremove -m 'checkin'
  adding .hgeol
  adding a.txt

Tag:

  $ hg tag 1.0

Rewrite .hgtags file as it would look on a new checkout:

  $ hg update -q null
  $ hg update -q

Touch .hgtags file again:

  $ hg tag 2.0

  $ cd ..