Conflict with git config

Hallo!

I’m not it’s a bug, but I can’t do brew update with these lines in .gitconfig:

[url "git@github.com:"]
    insteadOf = https://github.com/

Got an error about a wrong key.
Mostly, I need this to work with golang repos.
Should I open an issue in main repo about this?

That just seems like a wrong configuration on your part. What happens if you do cd $(brew --repo homebrew/core) && git fetch?