Can ARI-conforming clients be granted exemptions to relevant rate limits?

[Osiris]

@mholt

if the window changes, assume a revocation or some other sort of problem (or expected problem), so might as well renew right away to get ahead of it, or to have a longer period of time in which to ensure service.

If the window changes, it might be just as simple as a shift in load on the ACME server. As far as I know, it doesn't mean impeding doom...