When using the new style profiles we get conflicts when trying to
replace the old `home-path` derivation. To avoid this conflict we
delete the old `home-path` before the install.
Unfortunately, `nix profile` does not yet have a equivalent for
`nix-env --set` and we have to do this hackish workaround. See
https://github.com/NixOS/nix/issues/6349
for the associated issue in Nix.
Fixes#2848
(cherry picked from commit ccc9164b76)
071e28c869