title: Dataclass subclass does not inherit __repr__
body: <p>I am using Python <code>dataclasses</code> module backported from Python 3.7.
  I stumbled upon this behavior where a dataclass subclass does not inherit <code>__repr__</code>:</p>
  
  <pre><code>from dataclasses import dataclass
  
  @dataclass
  class Person:
      name: str
  
      def __repr__(self):
          return f'{self.__class__.__qualname__}({self.name})'
  
      def print_something(self):
          return self.name
  
  @dataclass
  class Employee(Person):
      title: str
  </code></pre>
  
  <p>Here is the output</p>
  
  <pre><code>In [21]: e = Employee(name='Dmitry', title='Systems Engineer')
  
  In [22]: p = Person(name='Dmitry')
  
  In [23]: repr(e)
  Out[23]: "Employee(name='Dmitry', title='Systems Engineer')"
  
  In [24]: p = Person(name='Dmitry')
  
  In [25]: repr(p)
  Out[25]: 'Person(Dmitry)'
  
  In [26]: p.print_something()
  Out[26]: 'Dmitry'
  
  In [27]: e = Employee(name='Dmitry', title='Systems Engineer')
  
  In [28]: repr(e)
  Out[28]: "Employee(name='Dmitry', title='Systems Engineer')"
  
  In [29]: e.print_something()
  Out[29]: 'Dmitry'
  </code></pre>
  
  <p>1) Why is this happening?<br>
  2) Is there a workaround for this behavior (except of redefining <code>__repr__</code> in the subclass)?</p>