more robust ISABELLE_HOME_USER for repository versions -- some versions of Emacs interpret foo//bar as /bar even on the command-line (unlike regular POSIX semantics);
--- a/etc/settings Wed Jan 11 00:05:31 2012 +0100
+++ b/etc/settings Wed Jan 11 15:12:57 2012 +0100
@@ -97,7 +97,7 @@
###
# The place for user configuration, heap files, etc.
-ISABELLE_HOME_USER="$HOME/.isabelle/$ISABELLE_IDENTIFIER"
+ISABELLE_HOME_USER="$HOME/.isabelle/${ISABELLE_IDENTIFIER:-.}"
# Where to look for isabelle tools (multiple dirs separated by ':').
ISABELLE_TOOLS="$ISABELLE_HOME/lib/Tools"