Index: java/client/org/apache/derby/client/am/Connection.java
===================================================================
--- java/client/org/apache/derby/client/am/Connection.java	(revision 472128)
+++ java/client/org/apache/derby/client/am/Connection.java	(working copy)
@@ -945,7 +945,11 @@
                                 java.sql.ResultSet.CONCUR_READ_ONLY,
                                 holdability());
             }
+
+            // Quick and dirty solution for DERBY-638
+            boolean savedInUnitOfWork = inUnitOfWork_;
             setTransactionIsolationStmt.executeUpdate("SET CURRENT ISOLATION = " + levelString);
+            inUnitOfWork_ = savedInUnitOfWork;
 
             isolation_ = level;
         }