should support testing particular bzr formats

[Martin Pool]

It would be useful to specify to usertest that a particular tool configuration should use a bzr format.

At the moment there is a hardcoded special case:

     80 self.compile_for_versions(TOOL_BZR, "development", """
     81 cd ..
     82 $tool init --development ${work_basename}-branchAndFix
     83 cd ${work_basename}-branchAndFix
     84 $tool pull ../$work_basename
     85 """)
     86

It would be better if the format could be configured and, if it's not the default, either an upgrade or init and pull would be run before testing starts.

[Martin Pool (mbp)]

At present scripts can use compile_for_versions, which must match against the name of the tool. That seems appropriate if it really is something that depends on the tool version, like a particular command being present or not. But setting the data format is not really dependent on the tool version, more a matter of how we want to test it.