RC2 does not seem to make use of the RedirectStrategy in buildRedirectUrlToLoginPage or buildHttpsRedirectUrlForRequest.
SEC-1153 has a comment by Luke Taylor noting configuration limitations for this class and the redirect strategy, though it's not clear (to me) exactly what it means, given that redirects in LoginUrlAuthenticationEntryPoint are not done via the strategy.
"Note that there are configuration limitations on the use of the redirect strategy for the standard LoginUrlAuthenticationEntryPoint (formerly AuthenticationProcessingFilterEntryPoint). For example, if it is attempting to redirect to an HTTPS URL, and a context-relative redirect strategy is used, then you will lose the HTTPS part. If necessary the entry point code should be overridden or a custom strategy should be written to make sure you end up with URLs that make sense to your clients and which work the way you want."
Particularly the comment "custom strategy should be written" seems to indicate that LoginUrlAuthenticationEntryPoint should be using the RedirectStrategy.
This ticket is the result of me trying to get context relative redirect URLs when launching the authentication entry point. Currently it seems I'd have to subclass.