lines_before_import is being ignored for files that only contain imports and comments

[robsdedude]

from a import b

as well as

# comment
from a import b

if run with lines_before_imports = 2 they should result in

 
 
from a import b

(ignore the spaces in the empty lines, they are needed for GH to display leading empty lines)

and

# comment


from a import b

respectively, but they don't. If you add any non-import statement to the files (e.g., foo = bar) the output is as expected.

[robsdedude]

I stumbled over this while investigating #1855