Code review comment for lp:~ian-clatworthy/bzr/411413-plugin-disable

This branch lets users disable selected plugins by adding settings to bazaar.conf. This can be helpful while tracking down problems and has been requested numerous times on the mailing list.

To generalise the feature, the setting for a given plugin can be an explicit (parent) directory to load a given plugin from. This lets developers/users run/test the default installation of a plugin say, rather than the first one found on the plugin search path.

Another test or two is required before this can land. I had a look at bzrib/tests/test_plugin.py and couldn't decide the best way to test this. TestLoadFromPath looks like the right class to extend but the way it monkey-patches the real code suggests otherwise? Input/advice/code welcome.

In terms of the big picture, my primary driver for this is better packaging. I'd like to see many more plugins bundled in the Windows and Mac installers but there's a risk in doing that. Being able to easily disable a suspect plugin reduces that risk a lot IMO.