Function calls with bound names fail

(Bug, Investigate , Priority: Critical, Test Status: No automated tests yet , Reported By Justin du Coeur, )
Summary: Not sure what the problem is, but it's thoroughly reproducible.
(I think Eric may have stumbled across this one before, but I'm recording this now that I have a solid recipe.)
Define a Function Property Recursive Func, like this:
$_1 -> _first -> +$hd
$_1 -> _rest -> +$tl
""[[$hd]] [[Recursive Func($tl)]]""
Then call it as:
[[Recursive Func(<""how"", ""now"", ""brown"", ""cow"">)]]
The result is:
how Didn't find a value for tl
This issue appears to be that a bound name that gets assigned to $_1 isn't getting resolved inside the function call. It should work, so this is a straight-up QL bug.