37328 Definer blows away current thread task

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@348770 13f79535-47bb-0310-9956-ffa450edef68

src/main/org/apache/tools/ant/taskdefs/Definer.java

@@ -421,7 +421,7 @@ public abstract class Definer extends DefBase {
             Antlib antlib = Antlib.createAntlib(getProject(), url, getURI());
             antlib.setClassLoader(classLoader);
             antlib.setURI(getURI());
-            antlib.perform();
+            antlib.execute();
         } catch (BuildException ex) {
             throw ProjectHelper.addLocationToBuildException(
                 ex, getLocation());