cue/testdata: add regression test for issue #2685
This issue was resolved by dynamic flat closedness in
https://cuelang.org/cl/1210790 so we only add a regression test here.
Closes #2685.
Signed-off-by: Daniel Martí <mvdan@mvdan.cc>
Change-Id: I5df1ed2b4d61a37fd6d77ab20d004c5e5409b6d8
Reviewed-on: https://cue.gerrithub.io/c/cue-lang/cue/+/1224701
Unity-Result: CUE porcuepine <cue.porcuepine@gmail.com>
Reviewed-by: Marcel van Lohuizen <mpvl@gmail.com>
TryBot-Result: CUEcueckoo <cueckoo@cuelang.org>