I am investigating an import issue with my pex file: in a virtual env or a clean environment my pex run fine; but it doesn't in my regular development environment. After some investigation, it turns out I have an older version of jinja2 (2.8) installed in

/usr/local/lib/python2.7/dist-packages/

and my application requires 2.10. Funny thing is before any of my code is executed, the python runtime already loaded a bunch modules, noticeably all

jinja2

sub-modules but not

jinaj2

itself. Then when my code is importing

jinja2

it would try to load some submodules and eventually fails with module not found error because the new version of

jinja2

was looking for some new functions in its sub-modules.