ASDF Issue with compiler warnings on ABCL

ASDF wraps its compilation process with WITH-COMPILATION-UNIT. On at least some implementations, this is necessary so that building doesn't emit spurious undefined function (variable, etc.) warnings. However, on ABCL, using WITH-COMPILATION-UNIT has the side effect of causing warnings to be intercepted and handled by HANDLE-WARNING. Then it seems that *resignal-compiler-warnings* is bound to NIL, and the compiler swallows them, instead of allowing them to flow down the stack to ASDF's handlers. In turn, this causes at least some of our regression tests to fail, because they check for expected warnings. This looks to me like a bug, but perhaps it's a feature ;-) Would you please explain and let us know how to handle this? thanks, r