Comment 3 for bug 519608

Ahh.. I see. In explorer/lib/app_suite.py we have:

try:
    import bzrlib.plugins.gtk
    app_suite_registry.register("gtk", ApplicationSuite("gtk",
        _GTK_STATELESS_MAPPING, _GTK_LOCAL_MAPPING, _GTK_REMOTE_MAPPING,
        fallbacks=['qbzr']),
        help="Applets from the bzr-gtk plugin")
except ImportError:
    pass

and in qbzr/lib/log.py we have:

try:
    from bzrlib.plugins.svn.repository import SvnRepository
    has_svn = True
except ImportError:
    has_svn = False

These will both cause explorer not to start as there is no
ImportError, but the plugins still can't be used.