title: Attribute Error: 'join' object has no attribute 'implicit_returning'
body: <p>I've the table model:</p>
  
  <pre><code>class Example(Base):
      __tablename__ = 'example'
  
      id = Column(ForeignKey(u'visit.id', ondelete=u'CASCADE', onupdate=u'CASCADE'), primary_key=True, unique=True)
      startdate = Column(Date, nullable=False)
      enddate = Column(Date)
  </code></pre>
  
  <p>And I try insert a new row:</p>
  
  <pre><code>session.begin()
  i = sqlalchemy.insert(Example)
  i = i.values({'id': 1, 'startdate': 1570798620, 'enddate': 1572526620})
  session.execute(i)
  session.commit()
  </code></pre>
  
  <p>But I get next error: <code>'Join' object has no attribute 'implicit_returning'</code>
  What is this problem?</p>