asserts $ISABELLE_OUTPUT_DIR;

--- a/lib/Tools/makeall	Tue Mar 18 18:02:19 1997 +0100
+++ b/lib/Tools/makeall	Tue Mar 18 18:20:26 1997 +0100
@@ -56,6 +56,7 @@
         echo '		**** Consider the -notest switch ****'
 esac
 
+mkdir -p $ISABELLE_OUTPUT_DIR
 
 case $FORCE.$EXEC in
   on.on) (cd $ISABELLE_OUTPUT_DIR;