clarified output (again);

--- a/src/Pure/Thy/export.scala	Fri Jan 11 22:34:28 2019 +0100
+++ b/src/Pure/Thy/export.scala	Fri Jan 11 22:35:04 2019 +0100
@@ -82,7 +82,7 @@
     name: String,
     body: Future[(Boolean, Bytes)])
   {
-    override def toString: String = uncompressed().toString
+    override def toString: String = name
 
     val name_elems: List[String] = explode_name(name)