add clean apt db to release script

Signed-off-by: Jessica Frazelle <acidburn@docker.com>

hack/make/release-deb

@@ -124,13 +124,15 @@ for dir in contrib/builder/deb/*/; do
 		-name *~${codename#*-}*.deb > "$APTDIR/dists/$codename/$component/filelist"
 done
 
+# clean the databases
+apt-ftparchive clean "$APTDIR/conf/apt-ftparchive.conf"
 
 # run the apt-ftparchive commands so we can have pinning
 apt-ftparchive generate "$APTDIR/conf/apt-ftparchive.conf"
 
 for dir in contrib/builder/deb/*/; do
 	version="$(basename "$dir")"
-	codename="${version//debootstrap-}"	
+	codename="${version//debootstrap-}"
 
 	apt-ftparchive \
 		-o "APT::FTPArchive::Release::Codename=$codename" \