# HG changeset patch
# User wenzelm
# Date 1493903451 -7200
# Node ID 79be5b464a1642389b539e3b6dad5d28ef126eea
# Parent  556c34fd0554aa81ae5accead93f5079fc66fa0b
more permissive, e.g. for system operations as in 678e00851cfb;

diff -r 556c34fd0554 -r 79be5b464a16 src/Pure/library.scala
--- a/src/Pure/library.scala	Thu May 04 14:58:19 2017 +0200
+++ b/src/Pure/library.scala	Thu May 04 15:10:51 2017 +0200
@@ -145,7 +145,7 @@
   def trim_substring(s: String): String = new String(s.toCharArray)
 
   def proper_string(s: String): Option[String] =
-    if (s == "") None else Some(s)
+    if (s == null || s == "") None else Some(s)
 
 
   /* quote */