Can't forward-reference an inner class when the outer class's base is also a forward reference

The following construct type-checked on mypy 0.650, but complains of an undefined name on 0.750. Sorry not to have a more precise range; I'm guessing the regression arrived with the new semantic analyzer.

class Outer(Base):
  field: Outer.Inner  # E: Name 'Outer.Inner' is not defined
  class Inner: pass
class Base: pass

All of the following are accepted, though:

# inner class before its use
class Outer(Base):
  class Inner: pass
  field: Outer.Inner
class Base: pass

# base before its use
class Base: pass
class Outer(Base):
  field: Outer.Inner
  class Inner: pass

# no base
class Outer:
  field: Outer.Inner
  class Inner: pass

Behavior is the same in all cases if I make the field annotation say just Inner rather than Outer.Inner. (IIRC I was using Outer.Inner because that made old mypy happier.)

This is mypy v0.750 on Python 3.6.5.

Inizia riproducendo gli esempi minimi con mypy 0.750 e confrontali con il comportamento segnalato di 0.650. Traccia il modo in cui l’analizzatore semantico gestisce la classe base della classe esterna e l’annotazione Outer.Inner. Il lavoro è completato quando la costruzione di forward reference supera il controllo dei tipi senza un errore di nome non definito e gli esempi accettati rimangono validi.