Direnv hangs in flake projects that add extra-substituters or extra-trusted-public-keys

[therealpxc]

Describe the bug
When an envrc is loading, it seems direnv doesn't or can't get user input from the shell, so if that envrc prompts Nix to do something interactive, like ask for user confirmation of binary caches that the project specifies, direnv just hangs indefinitely.

To reproduce

1. Create a new project using the flake-parts template.
2. Change nixConfig.extra-trusted-public-keys and nixConfig.extra-substituters to lists, and add entries for a binary cache that you've not previously interactively approved at your machine/as your user.
3. Run git init and then add the files from the template to the git index with git add .gitignore and then git add ..
4. Run direnv allow, and observe that direnv hangs forever. Although it will look like it's giving you a yes/no prompt, typing y or n and hitting enter will not do anything.

Workaround
You can hit CTRL+C to cancel the prompt from evaluating, and then run nix develop --impure. You'll be prompted to approve or reject the additional substituter and public key, but this time it'll be a real prompt that accepts your input. If you tell it to persist your decision, direnv evaluation will succeed after that.

Version
devenv: 1.2.0

[therealpxc]

Looks like this is caused by some kind of issue in direnv: direnv/direnv#1022