The supported version of ant is 1.7.1 for JavaFX 2.0. For developer convenience, we need to modify any build files that fail to build with ant 1.8.*, for example:

build-jogl:
     [exec]
     [exec] BUILD FAILED
     [exec] Property antlr.jar was circularly defined.
     [exec]
     [exec] Total time: 0 seconds
     [exec] Buildfile: D:\work\jfx\runtime\prism-jogl\make\build.xml

BUILD FAILED
D:\work\jfx\runtime\prism-jogl\build.xml:53: The following error occurred while executing this line:
D:\work\jfx\runtime\prism-jogl\build-windows.xml:22: exec returned: 1