s/an bug/a bug/

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@383569 13f79535-47bb-0310-9956-ffa450edef68

src/main/org/apache/tools/ant/ComponentHelper.java

@@ -958,7 +958,7 @@ public class ComponentHelper  {
                 }
             } else {
                 out.println();
-                out.println("This is not an bug; it is a configuration problem");
+                out.println("This is not a bug; it is a configuration problem");
             }
         }
         out.flush();