rejectedsoftware/vibe.d — pull request #869 by japplegame (2014-10-17 13:41:15+00:00)
Title: Fixes issue #868

`JsonStringSerializer.isSupportedValueType!(Nullable!T)` equals `true` if `T` is numeric type.
This causes `serializeImpl` to call `JsonStringSerializer.writeValue` which fails If `Nullable!T` is empty.