Install Trac on Apache2 using setup.py error

Question

I want to modify some code in Trac source code and build + install on apache2.

First, I use command apt-get install trac to install trac and running trac project on apache2 is no problem, but if I use source to build(python setup.py build), install (python setup.py install) and restart apache2, then apache2 will return Internal Server Error(500).

But if I run Trac in standalone mode, it will running without problem. So I think it might be a permission problem.

I put the source at /var/trac_1.0.9 and I tried to make the folder can be accessed by apache2 using chown -R www-data.www-data /var/trac_1.0.9 and find /var/trac_1.0.9-type d|xargs chmod g+sw, but it still not working.

I want to know how to solve this problem if I want to use source code to install Trac on apache2 instead of use apt-get method.

Thanks!

my env:

Ubuntu 16.04 LTS
Trac 1.0.9 [Github source][1]
Apache/2.4.18(Ubuntu)

and my .conf in apache2 (/etc/apache2/conf-enabled/trac.conf):

<Location /trac>
    SetHandler mod_python
    PythonInterpreter main_interpreter
    PythonHandler trac.web.modpython_frontend
    PythonOption PYTHON_EGG_CACHE /tmp/python_egg_cache
    PythonOption TracEnvParentDir /var/trac
</Location>