Describe the bug

I'm running nix unstable and I cannot do a garbage collection anymore, because my store contains a path with an 'illegal' character.

error: store path 'bbnr9kxadkp6bbq059ir25bxpvkgfl1p-gssdp-aarch64-unknown-linux-gnu-1.2.3.drv!bin' contains illegal character '!'

Steps To Reproduce

1. Not sure how to make those paths, but I guess it might be related to content-addressed derivations?

What I tried:

• sudo nix-collect-garbage --older-than 15d
• sudo nix-store --delete
• sudo nix store delete (doesn't work because path 'is not a flake')

Expected behavior

I can still do a garbage collection, even if it's just to remove the illegal directories.

nix-env --version output

nix-env (Nix) 2.4pre20210802_47e96bb

Additional context

Some experimental features are enabled, which may have caused this issue or be related to it:

experimental-features = nix-command flakes ca-derivations ca-references