[MERGE] Improve test_sprout_preserves_kind

[Aaron Bentley]

Aaron Bentley has voted abstain.
Status is now: Semi-approved
Comment:
The name of this test is quite misleading.  It is not actually 
preserving a target kind-- it is ensuring that the format can be 
overridden by specifying it.

For details, see: 
http://bundlebuggy.aaronbentley.com/project/bzr/request/%3C20081114063335.GK31377%40steerpike.home.puzzling.org%3E
Project: Bazaar