为什么子进程在这里抛出OSError？

I have written my own module, mainly handling a filefield for a django site. After messing around with some things related to mod_wsgi (solved by updating to 3.3), i got my code to run. Right after all the necessary imports, before defining any classes or functions, i test for the availability of sox, an audiocommandlinetool essential to some of my modules functions:I have written my own module, mainly handling a