SciTools/iris — pull request #1370 by rhattersley (2014-10-08 15:40:19+00:00)
Title: Correction to MDI handling.

Thanks to @bjlittle reporting some unexpected behaviour, further investigation into the handling of missing values by the ECMWF GRIB API has highlighted a misunderstanding:
- Keys with signed values return 2**32-1, and **not** -(2**31-1) as previously thought.

Happily, this makes things simpler. \o/