Minor pep8 fix.

[pp-mo]

I goofed the previous merge when I mis-edited the commit message + then manually corrected it.
It seems I inadvertently added back this change, which I thought I'd excluded but I probably squashed together in error.

This fixes.

[pp-mo]

Can someone attend @marqh @djkirkham ?
I just broke master, so let's not skip a review process again !

I have just double-checked that all commits from the last 2 PRs did get included.

What happened:
I merged from @djkirkham original PR #2240, the single commit here
I realised I had messed up writing the squashed commit message online.
So I checked out the new master, edited the commit message with "commit --amend" and modified the master direct with "push upstream/master -f"...

I did it that way because I specifically wanted to fix a broken commit message, so a PR wouldn't address it.

It looks like I included the change from @marqh additional commit, which I had not intended to include, and which I failed to purge when checking out the latest version of upstream/master.

[djkirkham]

Looks good to me