Running yapf on this block of code blasts a closing paren off towards the moon.

Running `yapf -i some_file.py` where `some_file.py` contains the following code:

Turns this
```
def some_function():
self.my_dictionary['some_member'] = \
self.some_method('This is a really long string that \
I need to split up with a backslash')
```

Into this
```
def some_function():
self.my_dictionary['some_member'] = \
self.some_method('This is a really long string that \
I need to split up with a backslash' )
```

And then turns the above into
```
def some_function():
self.my_dictionary['some_member'] = \
self.some_method('This is a really long string that \
I need to split up with a backslash' )
```

And so on and so fourth, creating an infinite formatting loop.