geogrid is failing in OLFS regression tests

Description

Here is an example curl request from the OLFS regression tests, it used to work but now returns a libdap error:

curl "http://localhost:8080/opendap/data/nc/coads_climatology.nc.dds?geogrid(SST,61,-82,38,-19)"
Error { 
    code = 500;
    message = "libdap exception building response: error_code = 1002: libdap error transmitting DDS: An internal error was encountered:
Unimplemented BaseType::read() method called for the variable named: SST
Please report this to support@opendap.org";
}

Probably this is a side effect of the recent changes we made to the DAS colliding with the geogrid heuristic.