[MERGE] Convert non-ascii blackbox tests to use internals where appropriate

[Martin Pool]

Martin Pool has voted approve.
Status is now: Semi-approved
Comment:
This looks like a useful cleanup.  It will clash textually but not 
conceptually with my test exception cleanup 
<http://bundlebuggy.aaronbentley.com/request/%3Ce01316480709180219l2306686dje6b75fcdce891c19%40mail.gmail.com%3E>, 
but that's ok.

 > tests.blackbox.test_non-ascii.test_missing fails (for each encoding) 
with incorrect return codes, but this is the case in bzr.dev so I didn't 
want to change this incorrectly.

Can you explain this more please?

It's testing that it returns 1 which is the correct result for missing 
as far as I can see.


For details, see: 
http://bundlebuggy.aaronbentley.com/request/%3C1189964091.18952.2.camel%40lapbert%3E