'write local nicas' fails when issued from a 4DEnsVar configuration

This issue is low priority (and saber related). When writing off the nicas parameters from a complete 4DEnsVar, the writing can fail because of NetCDF access conflicts. It looks like all subwindows are trying to write the same information in the same files at the same time.  
There is probably no real case of application of such a configuration, yet it is a tiny flaw.