Okay, PJE explained on the setuptools issue tracker that the .egg-info file needs to be in the sys.path. Currently the .egg-info file in the Debian/Ubuntu package is located in:
But /usr/share/python-support/python-nevow is not in the sys.path. Therefore setuptools doesn't see the .egg-info file when it searches the sys.path. so it doesn't think that Nevow is installed.
Okay, PJE explained on the setuptools issue tracker that the .egg-info file needs to be in the sys.path. Currently the .egg-info file in the Debian/Ubuntu package is located in:
zooko@deharo2:~$ dpkg --listfiles python-nevow | grep -i egg python- support/ python- nevow/Nevow- 0.9.26. egg-info
/usr/share/
But /usr/share/ python- support/ python- nevow is not in the sys.path. Therefore setuptools doesn't see the .egg-info file when it searches the sys.path. so it doesn't think that Nevow is installed.