For reasons lost to time, the implementation of [CLC #200][] that was merged inappropriately dropped `ExceptionContext` in the `toException` implementation given to `SomeException`. As noted in #27194, this results in loss of annotations, significantly impairing the usability of the backtrace facility. The proposal originally called for no change to `SomeException(toException)`, retaining its original implementation of `toException = id`. This should be fixed. [CLC #200]: https://github.com/haskell/core-libraries-committee/issues/200