yapf (facebook style) loves to make a two-step reformat of over-long line

YAPF loves to make two steps if run twice in fixing this:

# last character is column 87 with our indent
self.assertEqual(result.reason_not_added, "current preflight is still running")

becomes

self.assertEqual(result.reason_not_added,
                 "current preflight is still running")

next run it becomes

self.assertEqual(
    result.reason_not_added, "current preflight is still running"
)

Now, I like the last option best, and it’s what we want, but the fact we take consistently two steps to get there is a surprise. I’m not sure why it prefers the intermediate form once, but it happens often enough to feel “routine”.

[ambv]

This problem is inherent to YAPF’s rules that depend on the “current relative line location”. After a single reformatting that relative location might change, in which case it will have different penalties assigned. I haven’t got time to really work on this before, you’re probably have to wait until PyCon for me to get to this during sprints.

[ppolewicz]

I confirm that it now works correctly for both my code and the example supplied by @daniel-pittman.

Please release to pypi.