Allow users to configure default git branch name

[JonathanLorimer]

[Ericson2314]

(See https://github.com/kolloch/crate2nix/issues/205#issuecomment-941199516)

[QAston]

I had the same issue, but the root cause seems to be that the branch parameter in cargo is simply ignored by crate2nix and it's not the problem with the defaults.

[Ericson2314]

@QAston sorry I didn't respond sooner, are you saying this fix is insufficient on its own?

[QAston]

Yes, I think so. Might be a different problem though - my cargo file pointed to the correct branch but it was ignored by cargo.nix, maybe in the OP's case there was no branch set in cargo files.

[kolloch]

Heyo @QAston / @Ericson2314,

I am doing some clean up work... I guess we can close this?

[kolloch]

(otherwise reopen)

[QAston]

no idea, I moved on from nix, I hope I never have to go back