Normalize leading blank lines when moving imports

[amyreese]

Running µsort on this sort of input does what I would consider to be the "wrong thing":

import re

import usort
import trailrunner

print("hello")

This gets sorted into:

import re

import trailrunner

import usort

print("hello")

Ie, the leading blank line above import usort is kept when moving usort below trailrunner, even though they are in the same category.

[pmeier]

I stumbled over this behavior today. The documentation only mentions:

6. Normalize whitespace between imports as needed

That is quite nondescript. Maybe we can add a paragraph what this actually means when the behavior is no longer the "wrong thing"?