[Nix-dev] /bin in chroot builds

[Lluís Batlle i Rossell]

Hello,

I noticed the nixos nix.conf includes /bin in the build chroot.

I saw that perl, when using the system() command, it runs /bin/sh "on unix", the
manual says.

In ubuntu, /bin/sh happens to point to /bin/dash, and so that is not able to
parse a thing like "source $stdenv/setup".

The buildenv package consists of a perl builder calling:
  system("eval \"\$postBuild\"")

So, we can consider either buildenv or perl impure.

What do you think? Should we patch perl (a matter of stdenv-updates), or you
favour this impurity? I vote for the first.

I triggered the problem trying to build nixos in Ubuntu.

Regards,
Lluís.