title: Why is glob ignoring some directories?
body: <p>I'm trying to find all <code>*.txt</code> files in a directory with <code>glob()</code>. In some cases, <code>glob.glob('some\path\*.txt')</code> gives an empty string, despite existing files in the given directories. This is especially true, if <code>path</code> is all lower-case or numeric. 
  As a minimal example I have two folders <code>a</code> and <code>A</code> on my <code>C:</code> drive both holding one <code>Test.txt</code> file.</p>
  
  <pre><code>import glob
  files1 = glob.glob('C:\a\*.txt')
  files2 = glob.glob('C:\A\*.txt')
  </code></pre>
  
  <p>yields </p>
  
  <pre><code>files1 = []
  files2 = ['C:\\A\\Test.txt']
  </code></pre>
  
  <p>If this is by design, is there any other directory name, that leads to such unexpected behaviour?</p>
  
  <p>(I'm working on win 7, with Python 2.7.10 (32bit))</p>
  
  <p><strong>EDIT:</strong> (2019) Added an answer for Python 3 using <code>pathlib</code>.</p>