diff -r c28143ae38cd -r 692e428803c8 src/Pure/PIDE/xml.scala
--- a/src/Pure/PIDE/xml.scala	Mon May 22 15:19:44 2017 +0200
+++ b/src/Pure/PIDE/xml.scala	Mon May 22 19:34:01 2017 +0200
@@ -161,7 +161,7 @@
         lookup(x) match {
           case Some(y) => y
           case None =>
-            val z = Library.trim_substring(x)
+            val z = Library.isolate_substring(x)
             if (z.length > max_string) z else store(z)
         }
     private def cache_props(x: Properties.T): Properties.T =
@@ -169,7 +169,7 @@
       else
         lookup(x) match {
           case Some(y) => y
-          case None => store(x.map(p => (Library.trim_substring(p._1).intern, cache_string(p._2))))
+          case None => store(x.map(p => (Library.isolate_substring(p._1).intern, cache_string(p._2))))
         }
     private def cache_markup(x: Markup): Markup =
       lookup(x) match {