requested to merge michal/prevent-idna-test-failures-with-libidn2-2.2.0 into master
libidn2 2.2.0+ parses Punycode more strictly than older versions and thus "dig +idnin +noidnout xn--19g" fails with libidn2 2.2.0+ but succeeds with older versions.
We could preserve the old behavior by using the IDN2_NO_ALABEL_ROUNDTRIP flag available in libidn2 2.2.0+, but:
Removing the problematic check appears to be the simplest solution as it does not prevent the relevant block of checks in the "idna" system test from achieving its purpose, i.e. ensuring dig properly handles invalid U-labels.
 see upstream commit 241e8f486134793cb0f4a5b0e5817a97883401f5