bzr-crosscheck is a Bazaar plugin that checks that one branch matches another, both externally and in numerous internal ways. In particular, it can be useful to cross check branches like this when testing migration from one data format to another.
The easiest way to install this plugin is to either copy or symlink the directory into your ~/.bazaar/plugins directory. Be sure to rename the directory to crosscheck (instead of bzr-crosscheck).
See http://bazaar-vcs.org/UsingPlugins for other options such as using the BZR_PLUGIN_PATH environment variable.
To test the plugin after installation:
bzr selftest crosscheck