IZPack ant task is failing with "com.izforge.izpack.api.exception.CompilerException: Neither install file nor text specified "

I'm trying to build using the ant task plugin.

I've been trying to track down what is causing this.

I see that the ant task is creating a compilerData without the install
file or install text.

CompilerData compilerData = new CompilerData(compression, kind, null,
configText, basedir, output, compressionLevel);

Instead, it tries to set it with:
propertyManager.setProperty("izpack.file", file.toString());

But then it seems that when i get to CompilerConfig#getXMLTree(), it
bails because neither the install file nor install text have been set on
the CompilerConfig.