src/Pure/Thy/thy_header.scala

--- a/src/Pure/Thy/thy_header.scala	Sun Nov 05 16:57:03 2017 +0100
+++ b/src/Pure/Thy/thy_header.scala	Sun Nov 05 17:45:17 2017 +0100
@@ -127,7 +127,7 @@
       { case xs ~ yss => (xs :: yss).flatten }
 
     val abbrevs =
-      rep1(text ~ ($$$("=") ~! text) ^^ { case a ~ (_ ~ b) => (a, b) })
+      rep1sep(text ~ ($$$("=") ~! text) ^^ { case a ~ (_ ~ b) => (a, b) }, $$$("and"))
 
     val args =
       position(theory_name) ~