Inconsistent results with SPLIT_COMPLEX_COMPREHENSION

I created a small example file, which I'd like the formatter to leave alone when `SPLIT_COMPLEX_EXPRESSION` is true, but unfortunately it does not.

If you create a file with the contents,

```py
dat_files = [
filename
for input_dir in args.input_dirs
for filename in glob.glob(os.path.join(input_dir, "*.DAT"))
]
```

and then run `yapf --style='{SPLIT_COMPLEX_COMPREHENSION: true}'` on it, the comprehension value and first `for` loop are joined,

```py
dat_files = [
filename for input_dir in args.input_dirs
for filename in glob.glob(os.path.join(input_dir, "*.DAT"))
]
```

Unfortunately this doesn't make much sense, because `filename` is more associated with the inner loop, and having it right next to the outer loop (`for input_dir in args.input_dirs`) is messier.

However, the example on the main README.rst for SPLIT_COMPLEX_EXPRESSION does provide desired results ... so maybe there is an issue with the ordering of transformers or something.

Thanks!!