Fix remove_incompatible items
Fix remove_incompatible items

Using cyordereddict revealed a bug: we were deleting items in the dictionary
in the process of iterating over it. That is a bad idea.

drewokane/xray,hetland/xray,hetland/xray,jhamman/xarray,shoyer/xray,petercable/xray,NicWayand/xray,rabernat/xray,jhamman/xarray,rabernat/xray,jcmgray/xarray,markelg/xray,jhamman/xarray,shoyer/xarray,cpaulik/xray,markelg/xray,chunweiyuan/xarray,pydata/xarray,clarkfitzg/xray,clarkfitzg/xray,pydata/xarray,kjordahl/xray,kjordahl/xray,markelg/xray,cpaulik/xray,shoyer/xarray,pydata/xarray,jhamman/xray,xray/xray