Checkout notification flags
Checkout will invoke an options notification callback (notify_cb) for
certain cases - you pick which ones via notify_flags:
Returning a non-zero value from this callback will cancel the checkout. The non-zero return value will be propagated back and returned by the git_checkout_... call.
Notification callbacks are made prior to modifying any files on disk, so canceling on any notification will still happen prior to any files being modified.
Invokes checkout on conflicting paths.
Notifies about "dirty" files, i.e. those that do not need an update but no longer match the baseline. Core git displays these files when checkout runs, but won't stop the checkout.
Sends notification for any file changed.
Notifies about untracked files.
Notifies about ignored files.
Notifies about ignored files.