Netcdf load should workaround unexpected names in 'coordinates' #3644
Description
We encountered a file where loading fails due to a variable referencing as 'coordinates' a dimension that it doesn't actually use.
Simplified example CDL :
netcdf minimal_failcase {
dimensions:
length_scale = 1 ;
lat = 3 ;
variables:
float lat(lat) ;
lat:standard_name = "latitude" ;
lat:units = "degrees_north" ;
short lst_unc_sys(length_scale) ;
lst_unc_sys:long_name = "uncertainty from large-scale systematic errors" ;
lst_unc_sys:units = "kelvin" ;
lst_unc_sys:coordinates = "lat" ;
data:
lat = 0, 1, 2;
}
LOADING FAILS
with message"ValueError: Missing data dimensions for multi-valued DimCoord 'latitude'"
Proposal
Strictly, this is not good CF.
Cf-checker confirms this, saying "INFO: attribute coordinates is being used in a non-standard way".
However, we should probable be capable of gracefully working around this type of problem,
as we do for invalid 'unit' and 'standard_name'.