On what versions should Trac patches be based?
I see that alphas and release candidates come out a lot faster than "released" versions of Sage. Should development patches be based on these pre-releases or on the current release? Furthermore, if I spot a patch on Trac that is based on an older version of Sage, should I go ahead and re-base the patch?
Notably, I have not found a clear answer in the Developer's Guide.
UPDATE: When producing the next stable, are the patches which are based on pre-releases "back-rebased" to the current stable? If so, is this a reason at all to favor basing on the current stable, rather than on the latest pre-release?