关于with语句：在python上下文管理器中返回finally块

Return in finally block in python context manager

我最近在python的with语句中遇到了一个奇怪的行为。我有一个代码，它使用Python的上下文管理器回滚__exit__方法中的配置更改。经理在__exit__的finally块中有一个return False值。我在下面的代码中隔离了这种情况-唯一的区别是返回语句的缩进：

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class Manager1(object):

def release(self):
pass # Implementation not important

def rollback(self):
# Rollback fails throwing an exception:
raise Exception("A failure")

def __enter__(self):
print"ENTER1"

def __exit__(self, exc_type, exc_val, exc_tb):
print"EXIT1"
try:
self.rollback()
finally:
self.release()
return False # The only difference here!

class Manager2(object):

def release(self):
pass # Implementation not important

def rollback(self):
# Rollback fails throwing an exception:
raise Exception("A failure")

def __enter__(self):
print"ENTER2"

def __exit__(self, exc_type, exc_val, exc_tb):
print"EXIT2"
try:
self.rollback()
finally:
self.release()
return False # The only difference here!

在上面的代码中，回滚失败，出现异常。我的问题是，为什么Manager1的行为与Manager2不同。该异常不会在Manager1中的WITH语句之外抛出，也不会在Manager2中退出时抛出。

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with Manager1() as m:
pass # The Exception is NOT thrown on exit here

with Manager2() as m:
pass # The Exception IS thrown on exit here

根据__exit__文件：

If an exception is supplied, and the method wishes to suppress the
exception (i.e., prevent it from being propagated), it should return a
true value. Otherwise, the exception will be processed normally upon
exit from this method.

在我看来，在这两种情况下，出口都没有返回真值，因此在这两种情况下，不应压制例外。但是在Manager1中是这样的。有人能解释一下吗？

我使用的是python 2.7.6。