Set adjusted cd_type for incomplete BD image

If COMPLETE=0 is set, the content should rather be
"bluray/not_complete" instead of just "not_complete". This would allow
one to build offline usable Edu BDs.

tools/start_new_disc

@@ -199,7 +199,11 @@ if [ $DISKNUM = 1 ] ; then
             fi
         fi
     else
-        echo "not_complete" > $CDDIR/.disk/cd_type
+        if [ $DISKTYPE = BD ] ; then
+            echo "bluray/not_complete" > $CDDIR/.disk/cd_type
+        else
+            echo "not_complete" > $CDDIR/.disk/cd_type
+        fi
     fi
 
     if [ $NUM_ARCHES -gt 1 ]; then