RUN_ALL assumes default Contiki search path

tools/cooja/contiki_tests/RUN_ALL

@@ -23,10 +23,10 @@ done
 
 if [ -z "$CONTIKI" ]; then
   if [ -z "$CONTIKI_HOME" ]; then
-    echo Undefined variable: CONTIKI
-    exit 1
+  	CONTIKI_HOME=../../..
   fi
   CONTIKI=$CONTIKI_HOME
+  echo Undefined variable: CONTIKI. Using default: ${CONTIKI}
 fi
 
 if [ $MAIL -eq 1 ]; then
@@ -94,4 +94,4 @@ do
   bash RUN_TEST $TEST $LOG
 done
 
-mail_report
+mail_report