Currently, while nonsensical, it is technically possible to `recur` to a `^:once fn*` point.

Repro:

Proposed:

If recur to head and in :once, then turn off :once and don’t clear closed overs. This allows existing code in the wild to continue to work correctly (by ignoring the :once hint in this case).

This change is being made in the context of .

Alternative:

Make this a compile error and throw if recur attempted inside :once fn

This is useful so that code like `(future (recur))` doesn't compile, giving users the impression that it's supposed to work (see comments at for an example)

Patch: 0001-CLJ-2317-disallow-recur-to-once-fn.patch

Decided not to do this as there is existing code, especially code that combines macros that make :once fns with code that may recur without knowing that.