[Twisted-Python] "twistd" in Twisted 16.4.0 can't import modules/packages from current working directory

Sept. 1, 2016

      Hi all

I couldn't find Twisted-specific group, so posting here.

Recently Twisted 16.4.0 got released. Yesterday I've tried to upgrade it 
for my apps and got an error.

I've created simple example, which demonstrates it.

File service.tac:
=======================================
import os
from twisted.application import service, internet

import mymodule

application = service.Application("Demo application")
----------------------------------------

File mymodule.py:
========================================
def myfunction(asd):
     """ Stub function """
----------------------------------------

If you try to run it with twistd -y service.tac you'll get an error:
== output ==============================
Unhandled Error
Traceback (most recent call last):
   File 
"/usr/local/lib/python2.7/site-packages/twisted/application/app.py", 
line 648, in run
     runApp(config)
   File 
"/usr/local/lib/python2.7/site-packages/twisted/scripts/twistd.py", line 
25, in runApp
     _SomeApplicationRunner(config).run()
   File 
"/usr/local/lib/python2.7/site-packages/twisted/application/app.py", 
line 379, in run
     self.application = self.createOrGetApplication()
   File 
"/usr/local/lib/python2.7/site-packages/twisted/application/app.py", 
line 444, in createOrGetApplication
     application = getApplication(self.config, passphrase)
--- <exception caught here> ---
   File 
"/usr/local/lib/python2.7/site-packages/twisted/application/app.py", 
line 455, in getApplication
     application = service.loadApplication(filename, style, passphrase)
   File 
"/usr/local/lib/python2.7/site-packages/twisted/application/service.py", 
line 411, in loadApplication
     passphrase)
   File 
"/usr/local/lib/python2.7/site-packages/twisted/persisted/sob.py", line 
223, in loadValueFromFile
     eval(codeObj, d, d)
   File "service.tac", line 7, in <module>
     import mymodule
exceptions.ImportError: No module named mymodule

Failed to load application: No module named mymodule
----------------------------------------

The errors comes down to this: twistd script does not add current 
working directory to python path (or removes it, I don't know what 
exactly happens), so it fails to import any packages/modules from it. 
The issue does not appear in previous version (Twisted 16.3.2).

Any ideas what caused it?

[Twisted-Python] "twistd" in Twisted 16.4.0 can't import modules/packages from current working directory

Yuri