pkg/list/testdata: add regression test for issue #4171
The error message for list.IsSorted with list.Descending repeats
the error path, e.g. "Descending.less: Descending.less:".
For #4171.
Signed-off-by: Daniel Martí <mvdan@mvdan.cc>
Change-Id: Ie7bb2ba7fa528c0d7aa05272fac4499a60e1aa97
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1231146
TryBot-Result: CUEcueckoo <cueckoo@cuelang.org>
Unity-Result: CUE porcuepine <cue.porcuepine@gmail.com>
Reviewed-by: Matthew Sackman <matthew@cue.works>