title: class in a private/custom package is not callable when imported
body: <p>I have a git repo containing my custom python package.
  I install it using pip</p>
  <pre><code>pip install git+https://github.com/xxxx/my-package.git
  </code></pre>
  <p>The package name is mytest
  the code is under src/mytest and it contains 3 files</p>
  <pre><code>simple.py
  def add_one(number):
      return number + 1
  
  hard.py
  def add_one(number):
      return number + 1
  
  myclass.py
  class MyClass:
      def __init__(self, something):
  </code></pre>
  <p>I open a python shell and I type</p>
  <pre><code>from mytest import simple, hard
  simple.add_one(1)
  hard.add_one(1)
  </code></pre>
  <p>so far so good, then I run into trouble using MyClass</p>
  <pre><code>from mytest import MyClass
  
  mportError: cannot import name 'MyClass' from 'mytest' 
  </code></pre>
  <p>why does it work with simple functions and not a class?
  What am I missing?</p>