title: Subprocess changing directory
body: <p>I want to execute a script inside a subdirectory/superdirectory (I need to be inside this sub/super-directory first). I can't get <code>subprocess</code> to enter my subdirectory:</p>
  
  <pre><code>tducin@localhost:~/Projekty/tests/ve$ python
  Python 2.7.4 (default, Sep 26 2013, 03:20:26) 
  [GCC 4.7.3] on linux2
  Type "help", "copyright", "credits" or "license" for more information.
  &gt;&gt;&gt; import subprocess
  &gt;&gt;&gt; import os
  &gt;&gt;&gt; os.getcwd()
  '/home/tducin/Projekty/tests/ve'
  &gt;&gt;&gt; subprocess.call(['cd ..'])
  Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
    File "/usr/lib/python2.7/subprocess.py", line 524, in call
      return Popen(*popenargs, **kwargs).wait()
    File "/usr/lib/python2.7/subprocess.py", line 711, in __init__
      errread, errwrite)
    File "/usr/lib/python2.7/subprocess.py", line 1308, in _execute_child
      raise child_exception
  OSError: [Errno 2] No such file or directory
  </code></pre>
  
  <p>Python throws OSError and I don't know why. It doesn't matter whether I try to go into an existing subdir or go one directory up (as above) - I always end up with the same error.</p>