Describe the bug
When using buildFHSUserEnv in shell.nix, nix-shell properly sets up an FHS user environment with /usr/lib, /lib/... etc. When using lorri with the shame shell.nix, however, it is not properly setup.

To Reproduce
Steps to reproduce the behavior:

1. Install bazel
2. Use git to checkout https://github.com/dmayle/nixos-bazel-userenv-example
3. Change to the lorri subdirectory
4. direnv allow
5. bazel build proto/...

Expected behavior
The go library should build without errors

Metadata
lorri did not crash

$ lorri info --shell-file shell.nix
lorri version: 1.2
GC roots exist, shell_gc_root: "/home/douglas/.cache/lorri/gc_roots/081a257f0dbdd5f43a8cd34f7f43a626/gc_root/shell_gc_root"

$ uname -a
Linux nixos 5.10.22 #1-NixOS SMP Tue Mar 9 10:11:15 UTC 2021 x86_64 GNU/Linux

Additional context