I just tried abcl 0.20 with Snow, and compilation (done with asdf:compile-op) fails early with:
Compilation failed: Not an absolute pathname #P"\___jar___file___root___\**\*.*"
r11664 works fine. Sorry that I didn't check before the release, I remembered checking it not much time ago but evidently I was wrong (r12666 is two weeks old).
Alessio