The Ladybird Docs.gmk uses the JDK_VERSION variable as part of a URL
in the definition of the JAVADOCBOTTOM variable.

   http://java.sun.com/products/jdk/$(JDK_VERSION)/devdocs-vs-specs.html

For Ladybird, this will result in this URL, which will not work.

   http://java.sun.com/products/jdk/1.3.1/devdocs-vs-specs.html

All Ladybird documentation, and indeed all J2SE 1.3.x documention,
will be at http://java.sun.com/products/jdk/1.3/...., i.e., there
will be no directories with names of the form 1.3.x.