Comment 2 for bug 988289

It's not impossible that this is really due to the "xsltMaxDepth" setting being too low. The recursion depth is data dependent after all, so deeply recursive stylesheet calls could end up being blocked.

Sadly, the setting is a global variable in libxslt, so it's impossible to change it on a case-by-case basis in lxml. In the worst case, you can change it statically in libxslt's transform.c when you build it from sources.

For lxml 2.4, I'll add a method "XSLT.set_global_max_depth()" that you can use to change this setting globally.