--- /usr/lib/portage/bin/ebuild.sh.orig	2010-09-06 23:20:50.000000000 +0200
+++ /usr/lib/portage/bin/ebuild.sh	2010-09-06 23:21:13.000000000 +0200
@@ -382,7 +382,8 @@
 				assert "$myfail"
 				;;
 			ZIP|zip|jar)
-				unzip -qo "${srcdir}${x}" || die "$myfail"
+				yes "n" | unzip -qo "${srcdir}${x}"
+				assert "$myfail"
 				;;
 			gz|Z|z)
 				_unpack_tar gzip