ImportError: No module named xen... on fresh compiled Xen 4.0.1 with Debian/Ubuntu

This took me a few hours to find in the mailing list and I thought I would share it with a title that people would find if googling for a solution. I compiled a fresh copy of Xen 4.0.1 and all of the tools that come along with it. I immediately rebooted and tried to run "xm" to check the status of the system. Any variation on any xen-related command led to me something along the lines of this:
ImportError: No module named xen.xm
The cause is that xen installs all of the python tools into ´╗┐´╗┐/usr/lib/python2.6/site-packages/ which is not by default in pythons path on a Debian (or Ubuntu)┬ámachine. After several hours of searching I found this post describing the solution.

When installing the compiled tools, pass this option to the makefile:
make install-tools PYTHON_PREFIX_ARG="--install-layout=deb"