title: IOError: no such file when file exists
body: <p>I've written simple script to update my CSS styles (from less to css) every time when i change less file. I have now:</p>
  
  <pre><code>import time
  import hashlib
  from subprocess import call
  
  
  def md5_checksum(filePath):
      fh = open(filePath, 'rb')
      m = hashlib.md5()
      m.update(fh.read())
      fh.close()
      return m.hexdigest()
  
  md5 = md5_checksum('styles.less')
  
  while True:
      newmd5 = md5_checksum('styles.less')
      if md5 != newmd5:
          sh = open('styles.css', 'w')
          call(['lessc', 'styles.less'], stdout=sh)
          md5 = newmd5
          sh.close()
          print 'Changed'
      time.sleep(0.2)
  </code></pre>
  
  <p>And what is strange, script is working for some time:</p>
  
  <pre><code>Changed
  Changed
  Changed
  Changed
  Traceback (most recent call last):
    File "watcher.py", line 16, in &lt;module&gt;
      newmd5 = md5_checksum('styles.less')
    File "watcher.py", line 7, in md5_checksum
      fh = open(filePath, 'rb')
  IOError: [Errno 2] No such file or directory: 'styles.less'
  </code></pre>
  
  <p>Whats going on? File is still there for 100%. What am i doing wrong?</p>