A gist that shows how you how to create a custom split callback for the bufio scanner that lets you go until a delimiter that is more than one byte long.

custom_scanner_split.go

// SplitAt returns a bufio.SplitFunc closure, splitting at a substring
// scanner.Split(SplitAt("\n# "))
func SplitAt(substring []byte) func(data []byte, atEOF bool) (advance int, token []byte, err error) {
	return func(data []byte, atEOF bool) (advance int, token []byte, err error) {

		// Return nothing if at the end of the file and no data passed
		if atEOF && len(data) == 0 {
			return 0, nil, nil
		}

		// Find the index of the input of the separator substring
		if i := bytes.Index(data, substring); i >= 0 {
			return i + len(substring), data[0:i], nil
		}

		// If at the end of the file with data, return the data
		if atEOF {
			return len(data), data, nil
		}

		return
	}
}