[MERGE][BUG #328135][1.12] Fix 'bzr init --development-wt5'

[Vincent Ladeuil]

>>>>> "jam" == John Arbash Meinel <john at arbash-meinel.com> writes:

<snip/>

    jam> Instead, it just does what the rest of the code does, and uses the
    jam> lazily imported attribute from 'bzrlib.workingtree'. I chose this as it
    jam> was the simple fix that got the job done.

    jam> I think it is semi-critical for 1.12, as otherwise none of the
    jam> --development-wt5 formats are actually available. (The patch is against
    jam> the bzr.1.12 branch.)

BB:approve

        Vincent