Two unnecessary blank lines added before the comment

Hello,
I have checked the following code (which is consistent with PEP8):
```
def foo():
if True:
a = 5
# }
```
and found that it is formatted by yapf as follows:
```
def foo():
if True:
a = 5

# }
```
Seems that this is a bug because there is no other function after the comment. Even if the code of `foo()` continues after the comment, two blank lines are added.