ALEXANDRIA:COPY-STREAM currently calls (< start end) even when END is NIL. This breaks COPY-FILE unconditionally and COPY-STREAM whenever END (or, less likely, START) is NIL.

for the record, it's fixed now.

and also for the record, there's no consensus in keeping the entire io.lisp in alexandria, and therefore it'll probably land in some more general and bigger utility library eventually.

and meanwhile, there are no tests... so, sorry for the breakage!