more robust invocation via ISABELLE_JDK_HOME and SCALA_HOME;

--- a/lib/Tools/java	Sat Apr 14 13:05:59 2012 +0200
+++ b/lib/Tools/java	Sat Apr 14 14:36:36 2012 +0200
@@ -12,6 +12,6 @@
   SERVER=""
 fi
 
-exec "$ISABELLE_JDK_HOME/bin/java" -Dfile.encoding=UTF-8 $SERVER \
+isabelle_jdk java -Dfile.encoding=UTF-8 $SERVER \
   "-Djava.ext.dirs=$("$ISABELLE_HOME/src/Tools/JVM/java_ext_dirs")" "$@"
 

--- a/lib/scripts/getsettings	Sat Apr 14 13:05:59 2012 +0200
+++ b/lib/scripts/getsettings	Sat Apr 14 14:36:36 2012 +0200
@@ -95,18 +95,27 @@
 
 #robust invocation via ISABELLE_JDK_HOME
 function isabelle_jdk () {
-  [ -z "$ISABELLE_JDK_HOME" ] && \
-    { echo "Unknown ISABELLE_JDK_HOME -- Java tools unavailable" >&2; return 2; }
-  local PRG="$1"; shift
-  "$ISABELLE_JDK_HOME/bin/$PRG" "$@"
+  if [ -z "$ISABELLE_JDK_HOME" ]; then
+    echo "Unknown ISABELLE_JDK_HOME -- Java tools unavailable" >&2
+    return 2
+  else
+    local PRG="$1"; shift
+    "$ISABELLE_JDK_HOME/bin/$PRG" "$@"
+  fi
 }
 
 #robust invocation via SCALA_HOME
 function isabelle_scala () {
-  [ -z "$SCALA_HOME" ] && \
-    { echo "Unknown SCALA_HOME -- Scala unavailable" >&2; return 2; }
-  local PRG="$1"; shift
-  "$SCALA_HOME/bin/$PRG" "$@"
+  if [ -z "$ISABELLE_JDK_HOME" ]; then
+    echo "Unknown ISABELLE_JDK_HOME -- Java tools unavailable" >&2
+    return 2
+  elif [ -z "$SCALA_HOME" ]; then
+    echo "Unknown SCALA_HOME -- Scala unavailable" >&2
+    return 2
+  else
+    local PRG="$1"; shift
+    "$SCALA_HOME/bin/$PRG" "$@"
+  fi
 }
 
 #CLASSPATH convenience

--- a/src/Tools/JVM/java_ext_dirs	Sat Apr 14 13:05:59 2012 +0200
+++ b/src/Tools/JVM/java_ext_dirs	Sat Apr 14 14:36:36 2012 +0200
@@ -19,5 +19,5 @@
 
 isabelle_jdk java \
   -classpath "$(jvmpath "$ISABELLE_HOME/src/Tools/JVM/java_ext_dirs.jar")" \
-  isabelle.Java_Ext_Dirs "$(jvmpath "$ISABELLE_HOME/lib/classes/ext")"
+  isabelle.Java_Ext_Dirs "$(jvmpath "$ISABELLE_HOME/lib/classes/ext")" 2>/dev/null