Function cargo::core::global_cache_tracker::is_silent_error

pub fn is_silent_error(e: &Error) -> bool

Returns whether or not the given error should cause a warning to be displayed to the user.

In some situations, like a read-only global cache, we don’t want to spam the user with a warning. I think once cargo has controllable lints, I think we should consider changing this to always warn, but give the user an option to silence the warning.