split_before_first_argument inconsistent behavior

I use "split_before_first_argument = false" with yapf of latest vesion 0.30. But I found the result is little inconsistent , for example,
```
order = COrder("objects", False, "", False, False, "","hhhhhhhhhhh", price=12555, vol=1)
```
the above code would be formated as :
```
order = COrder("objects",
False,
"",
False,
False,
"",
"hhhhhhhhhhh",
price=12555,
vol=1)
```
That is what it should be, but if I add a comment char '#' in one parameter line, like this:
```
order = COrder("objects",
False,
"",
False,
False,
"",
"hhhhhhhhhhh",
price=12555, #
vol=1)
```
then after reformattng, the 1st line is changed:
```
order = COrder(
"objects",
False,
"",
False,
False,
"",
"hhhhhhhhhhh",
price=12555, #
vol=1)
```

I wonder whether it is supposed to be so , or it is a bug.