Dictionary comments are oddly and inconsistently indented with SPLIT_ALL_TOP_LEVEL_COMMA_SEPARATED_VALUES

Reproducible example:

```python
table = {
# Description #1
"foo": "lorem ipsum dolor est",

# Description #2
"bar": "lorem ipsum dolor est",

# Description #2
"baz": "lorem ipsum dolor est",
}
```
with a `.style.yapf` file:
```
[style]
SPLIT_ALL_TOP_LEVEL_COMMA_SEPARATED_VALUES = True
```
running `yapf --diff` (0.31.0) outputs:
```
@@ -2,9 +2,9 @@
# Description #1
"foo": "lorem ipsum dolor est",

- # Description #2
+ # Description #2
"bar": "lorem ipsum dolor est",

- # Description #2
+ # Description #2
"baz": "lorem ipsum dolor est",
}
```
The first comment was left alone, but the subsequent comments were inexplicably(?) unindented by two spaces.