On hpux ia64, the shared library extension should be
".so".  This is currently problematic in that other
add-on python modules (such as those for subversion)
correctly detect the host_os/host_cpu and build
_module.so, which is not seen by python built using ".sl".

According to
http://devresource.hp.com/drc/resources/portguideipf/index.jsp#dynlinkfac


"Shared library names

Since dynamic linking APIs operate on shared libraries,
it is also important to note that the shared library
naming scheme on Linux is lib*.so; whereas, on HP-UX
11i Version 1.5 the naming scheme is lib*.sl for PA and
lib*.so on IPF. Also APIs may reside in different
libraries files on Linux and HP-UX, so you may need to
dynamically load a different shared library name on
HP-UX and Linux."

To translate this quote, PA=hppa and IPF=ia64.