nix: --add-root fails with unexpected permission error

#118
Opened by tazjin at 2021-04-11T12·11+00

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.

From IRC:

<+Remosi> what about strace -f -etrace=symlink .... ? <+Remosi> and see if there's an EPERM in there