symlinks: minimal support for symlinks in merge/update
This will get angry, confused, and sad if you try to merge a symlink
with a regular file.
#!/bin/sh
mkdir t
cd t
hg init
echo a > a
hg add a
hg commit -m test -d "1000000 0"
rm .hg/requires
hg tip
echo indoor-pool > .hg/requires
hg tip
true