tests/test-no-symlinks.t

changectx: increase perf of walk function

When running 'hg cat -r . <file>' it was doing an expensive ctx.walk(m) which
applied the regex to every file in the manifest.

This changes changectx.walk to iterate over just the files in the regex, if no
other patterns are specified. This cuts hg cat time by 50% in our repo and
probably benefits a few other commands as well.

  $ "$TESTDIR/hghave" no-symlink || exit 80

# The following script was used to create the bundle:
#
# hg init symlinks
# cd symlinks
# echo a > a
# mkdir d
# echo b > d/b
# ln -s a a.lnk
# ln -s d/b d/b.lnk
# hg ci -Am t
# hg bundle --base null ../test-no-symlinks.hg

Extract a symlink on a platform not supporting them

  $ hg init t
  $ cd t
  $ hg pull -q "$TESTDIR/bundles/test-no-symlinks.hg"
  $ hg update
  4 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat a.lnk && echo
  a
  $ cat d/b.lnk && echo
  d/b

Copy a symlink and move another

  $ hg copy a.lnk d/a2.lnk
  $ hg mv d/b.lnk b2.lnk
  $ hg ci -Am copy
  $ cat d/a2.lnk && echo
  a
  $ cat b2.lnk && echo
  d/b

Bundle and extract again

  $ hg bundle --base null ../symlinks.hg
  2 changesets found
  $ cd ..
  $ hg init t2
  $ cd t2
  $ hg pull ../symlinks.hg
  pulling from ../symlinks.hg
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 6 changes to 6 files
  (run 'hg update' to get a working copy)
  $ hg update
  5 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat a.lnk && echo
  a
  $ cat d/a2.lnk && echo
  a
  $ cat b2.lnk && echo
  d/b