for some reason, this yields quite different results for norne than
the default variant, e.g. when comparing PRESSURE, we get
```
> compareECL -k PRESSURE -t UNRST ebos/NORNE_ATW2013 ebos_altidx/NORNE_ATW2013 1 1e-4
Comparing 'ebos/NORNE_ATW2013' to 'ebos_altidx/NORNE_ATW2013'.
Comparing PRESSURE...
Occurrence in first file = 9
Occurrence in second file = 9
Value index = 0
(first value, second value) = (254.195, 253.191)
Program threw an exception: [/home/and/src/opm-common/build-cmake/fake-src/examples/test_util/EclRegressionTest.cpp:161] Deviations exceed tolerances.
The absolute deviation is 1.00311, and the tolerance limit is 1.
The relative deviation is 0.00394624, and the tolerance limit is 0.0001.
```
IMO this is a bug, but the reasons for it are currently unknown.
