SPLIT_ARGUMENTS_WHEN_COMMA_TERMINATED doesn't considered?

Thank you all for this amazing command! I've beeing using this command in many different project with different rules and styles and it just rocks!

Today, I'm mixing this command with `add-trailing-comma` (https://github.com/asottile/add-trailing-comma) and while testing the run of both I found some strange behaviour in yapf.

It seems that `SPLIT_ARGUMENTS_WHEN_COMMA_TERMINATED` is not considered when running:

```diff
$ yapf --diff --style='{based_on_style: pep8, SPLIT_ARGUMENTS_WHEN_COMMA_TERMINATED: False}' trailing-example.py
--- trailing-example.py (original)
+++ trailing-example.py (reformatted)
@@ -1,4 +1,22 @@
def myfunc(
- a, b, c, d, e, f, argument, larger, here, to, reach, eighty, lines,
+ a,
+ b,
+ c,
+ d,
+ e,
+ f,
+ argument,
+ larger,
+ here,
+ to,
+ reach,
+ eighty,
+ lines,
):
- a = [1, 2, 3, 4, 5,]
+ a = [
+ 1,
+ 2,
+ 3,
+ 4,
+ 5,
+ ]
$ yapf --version
yapf 0.21.0
```

I supposed that it shouldn't change anything in the above example since it should not split when comman terminated. Am I missing something? Thanks!