The removed lines converted the flake path passed by the command line
from `/some/path` to `git+file:///some/path`.

This technically shouldn't cause any issues, however running
`nixos-rebuild switch` inside a directory `/nix/store` will cause the
switch to fail and leave a partially construct generation (see issue #144811
for details).

By itself this shouldn't be too much of an issue, however thanks to
another issue in `systemd-boot-builder.py` this can leave the system
in a broken state for those using `boot.loader.systemd-boot` (AFAIK the
default), where future `nixos-rebuild switch` will fail
(see issue #93694 for details).

The issue can be fixed by running
`nix-env -p /nix/var/nix/profiles/system --delete-generations old`,
however this makes newbies very confused and it is showing in our
support threads in Matrix and Discourse (see
https://discourse.nixos.org/t/need-help-on-failure-of-building-my-configuration/16842).

Keep in mind this is a workaround. The actual issue seems to be in nix
itself (see: NixOS/nix#5510).

See also #150065 for an alternative fix that caused other issues.

Kudos for @figsoda for figuring out this fix.

(cherry picked from commit c274d04)