This milestone is for any backwards-compatible changes we want to backport to the stable/0.5 branch. We may not actually tag a 0.5.1 release; we will be more likely to do so if we backport some bug fixes, as documentation improvements are deployed immediately.

We should close this milestone when we either (i) release 0.5.1; or (ii) discontinue the stable/0.5 branch once 0.6.0 has been released.