fixed exception text appears twice

Author: emacarron

src/main/java/org/mybatis/spring/MyBatisExceptionTranslator.java

@@ -70,7 +70,7 @@ public DataAccessException translateExceptionIfPossible(RuntimeException e) {
             }
             return this.exceptionTranslator.translate(e.getMessage() + "\n", null, (SQLException) e.getCause());
         }
-        return new MyBatisSystemException(e.getMessage(), e);
+        return new MyBatisSystemException(e);
     }
 
    /**

src/main/java/org/mybatis/spring/MyBatisSystemException.java

@@ -31,8 +31,8 @@ public class MyBatisSystemException extends UncategorizedDataAccessException {
 
     private static final long serialVersionUID = -5284728621670758939L;
 
-    public MyBatisSystemException(String msg, Throwable cause) {
-        super(msg, cause);
+    public MyBatisSystemException(Throwable cause) {
+        super(null, cause);
     }
 
 }