waitSeconds is not respected when requiring in errback

[wuservices]

I created this example to show that waitSeconds isn't respected when calling require in an errback to retry loading something: https://jsfiddle.net/j7L0mzka/.

The big issue with that is, I can't retrying loading a module a few times or retry and show the user an error after a timeout.

I'm trying to implement auto-retry behavior in the errback (similar to #1352). Currently, we have a long waitSeconds, but looking at all the real user errors, it seems like this doesn't help for some people. Instead, it would be great to retry loading the same module and use a shorter waitSeconds. I'm guessing this will be especially good for people with a flakey mobile connection.