[patch] exclude .bzrignore from export, this time with tests

[Jamie Wilkinson]

This one time, at band camp, John A Meinel wrote:
>I would just do:
>
>mkdir a
>cd a
>bzr init
>echo a > a
>bzr add
>bzr commit -m a
>bzr ignore 'something'
>bzr commit -m "ignoring"
>
>bzr export ../dir_export
>
>cd ..
>files = sorted(os.listdir('dir_export'))
>self.assertEqual(['a'], files)
>
>Naturally the above needs to be changed into python commands. But I
>think it gives the idea. Just do an export to a directory, and make sure
>that there is no .bzr/ directory and no .bzrignore file.
>If you have the test, it won't re-appear.

Neat, it was the listdir part I had the mental block on :)

Committed at revno 1528 in the same branch.