NAN == NAN for regression testing
Unfortunately a number of inputs to the flavor taggers are sometimes NAN. This is fine from a computing and physics point of view: it's reproducible and the downstream code handles these inputs fine. The place where it's not fine is in the frozen derivation tests: our diff script recognizes two files with identical branches as different because NAN != NAN
according to IEEE standards.
Since this isn't actually a difference from the regression testing point of view, this gives acmd diff-root
an option to allow NAN == NAN
.
This is a followup for !28552 (closed)