etc/settings

--- a/etc/settings	Sun Dec 09 00:08:59 2018 +0100
+++ b/etc/settings	Sun Dec 09 12:09:54 2018 +0100
@@ -68,6 +68,7 @@
 ###
 
 ISABELLE_COMPONENT_REPOSITORY="https://isabelle.in.tum.de/components"
+ISABELLE_COMPONENTS_BASE="$USER_HOME/.isabelle/contrib"
 
 # The place for user configuration, heap files, etc.
 if [ -z "$ISABELLE_IDENTIFIER" ]; then