Create extension that can disable symlink support:

  $ cat > nolink.py <<EOF

  > from mercurial import extensions, util

  > def setflags(orig, f, l, x):

  >     pass

  > def checklink(orig, path):

  >     return False

  > def extsetup(ui):

  >     extensions.wrapfunction(util, 'setflags', setflags)

  >     extensions.wrapfunction(util, 'checklink', checklink)

  > EOF

  $ hg init unix-repo

  $ cd unix-repo

  $ echo foo > a

  $ ln -s a b

  $ hg ci -Am0

  adding a

  adding b

  $ cd ..

Simulate a checkout shared on NFS/Samba:

  $ hg clone -q unix-repo shared

  $ cd shared

  $ rm b

  $ echo foo > b

  $ hg --config extensions.n=$TESTTMP/nolink.py status --debug

  ignoring suspect symlink placeholder "b"

Make a clone using placeholders:

  $ hg --config extensions.n=$TESTTMP/nolink.py clone . ../win-repo

  updating to branch default

  2 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ cd ../win-repo

  $ cat b

  a (no-eol)

  $ hg --config extensions.n=$TESTTMP/nolink.py st --debug

Write binary data to the placeholder:

  >>> open('b', 'w').write('this is a binary\0')

  $ hg --config extensions.n=$TESTTMP/nolink.py st --debug

  ignoring suspect symlink placeholder "b"

Write a long string to the placeholder:

  >>> open('b', 'w').write('this' * 1000)

  $ hg --config extensions.n=$TESTTMP/nolink.py st --debug

  ignoring suspect symlink placeholder "b"

Commit shouldn't succeed:

  $ hg --config extensions.n=$TESTTMP/nolink.py ci -m1

  nothing changed

  [1]

Write a valid string to the placeholder:

  >>> open('b', 'w').write('this')

  $ hg --config extensions.n=$TESTTMP/nolink.py st --debug

  M b

  $ hg --config extensions.n=$TESTTMP/nolink.py ci -m1

  $ hg manifest tip --verbose

  644   a

  644 @ b