Fix increment/decrement bug.

PR: 4549
Obtained from:
Submitted by:
Reviewed by:


git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@269849 13f79535-47bb-0310-9956-ffa450edef68

src/main/org/apache/tools/ant/taskdefs/optional/PropertyFile.java

@@ -546,10 +546,10 @@ public class PropertyFile extends Task
                 newValue = value;
             }
             else if (m_operation == Operation.INCREMENT_OPER) {
-                newValue += value;
+                newValue = ++value;
             }
             else if (m_operation == Operation.DECREMENT_OPER) {
-                newValue -= value;
+                newValue = --value;
             }
             m_value = fmt.format(newValue);
         }