Failure.DESTROY warning sometimes warns when Failure was technically handled

[zoffixznet]

Originally started in #1298 This problem was spotted in one of our tests.

Usually Failure.DESTROY warning about unhandled Failures is good, but there is this edge case where more than one Failure is involved:

22:04 |   | e: use Test; for ^1000 { my $ = Failure.new < Failure.new; CATCH { default {} } }
-- | -- | --
22:04 | evalable6 | Zoffix, rakudo-moar 8ba3c86e7: OUTPUT: «WARNING: unhandled Failure detected in DESTROY. If you meant to ignore it, you can mark it…»
22:04 |   | Zoffix, Full output: https://gist.github.com/06e558ac81c8f261ad2d9c5236b06cfa

The exlosion happens when .Real is called inside < op, but the explosion of the first Failure prevents the second Failure from ever exploding, resulting in warnings for failures that weren't technically left unhandled.