alignment bug in the presence of tabs

I'm using stylish-haskell 0.13.0.0 without any configuration. Note how it inserts a space in the middle of a literal in the last line of the example below. This only happens when the code is indented using tabs.
```
$ cat test.hs
x = 1 where
y ab = 1
y x = 12345678

$ stylish-haskell test.hs
x = 1 where
y ab = 1
y x = 12345 678
```