Replace the previous logic of running the whole Makefile again on any failure, with wrapping all git clone and fetch commands in a new retry_with_backoff_time function that actually sleeps before retrying (a random amount of seconds to make less requests at once), and retries up to 5 times, each time with likely more sleep time.
With this change it is more likely to succeed and we have less confusing output as deps/Makefile will not run twice if it fails for any reason (e.g. a syntax error).
