mike-burns/aeson — comment on commit 4fbd5b9139d487dd7eb00fe5674e424489a85b7c
File: Data/Aeson/Types/Class.hs line 623
By mike-burns:

You're right, this would produce an invalid JSON date.

I can't think of a better solution than using `take`. Ideally the time formatter would take a numeric offset so we could say `%3Q`, but no such luck yet.