Trying to use
nix-instantiate --add-root in build scripts (to create gcroots) fails with
permission denied errors, however
ln -s $foo $bar works fine. For now in [cl/2904](https://cl.tvl.fyi/c/depot/+/2904) we will use
ln, but it would be nice to figure out what the reason for this is.
<+Remosi> what about strace -f -etrace=symlink .... ? <+Remosi> and see if there's an EPERM in there