Formatting the file adds a space in the first line

Have a file `bug.lua` in the editor:

~~~lua
#! /usr/bin/lua
~~~

What steps will reproduce the issue?
1. Press Ctrl+Alt+L to format the file

What is the expected result?

Nothing happens since the file already looks fine.

What happens instead?

A space is added between the `#!` and the `/usr/bin/lua`.
Pressing Ctrl+Alt+L again adds another space, and so on.