fix --nan-equal as in MR30195

Merged Julien Maurer requested to merge cherry-pick-f9725df0 into 21.0-mc16a

(cherry picked from commit f9725df0)

follow up of !62927 (merged), I had not noticed that the original implementation has been subsequently corrected (and the TCT tests in the last nightly indeed failed because of that).

there should have been a similar follow-up MR for 21.0-mc16d but due to a wrong manipulation pushed the commit directly to that branch...

Merge request reports