Hi,The zygrib package is dead upstream, having being replaced by xygrib which entered sid yesterday (Thank you for your timeliness!)
Please remove zygrib from testing and unstable. Thanks Alastair McKinstry (zygrib and xygrib maintainer) -- Alastair McKinstry, <alastair.mckinstry@ichec.ie>, t: +353 1 5241608 x68 Environmental Sciences Activity Leader, ICHEC, IT 301, NUI Galway, Ireland