In Python3, dict.keys() returns a view object rather than a list. This
behaves differently in that changes to the dict also modify the view, and
in that the view type interacts with various operators in different ways to
lists.
One universally correct transformation to preserve Python2 behaviour in
Python3 would be to replace all instances of d.keys() with
list(six.iterkeys(d)), and indeed we did. However, like many automatic
transformations the results are usually unsightly, invariably inefficient,
and frequently absurd. Not least because list(d.keys()) and indeed list(d)
are also equivalent.
This patch changes to using the simplest correct method of accessing the
data we want in each case.
This reverts or rewrites most of commit
4ace95ad47da7099191a06325c5d0b156fd54894.
Change-Id: Iba3cf48246d8cbc958d8fb577cd700a218b0bebf
5566e6f2c8