diff -up sage-5.9/spkg/build/sage-5.9/module_list.py.orig sage-5.9/spkg/build/sage-5.9/module_list.py --- sage-5.9/spkg/build/sage-5.9/module_list.py.orig 2013-03-19 18:13:55.457986912 -0300 +++ sage-5.9/spkg/build/sage-5.9/module_list.py 2013-03-19 18:14:03.785987230 -0300 @@ -1988,7 +1988,7 @@ ext_modules = [ def is_package_installed(name): return False -if is_package_installed('fes'): +if 1: ext_modules.extend([ Extension("sage.libs.fes", ["sage/libs/fes.pyx"],