[BUG] bzr.exe is unable to load built-in plugin 'launchpad'

[Alexander Belchenko]

I just discover (when test bzr.exe on clean machine) that standalone 
bzr.exe unable to load and use built-in plugins 'launchpad'.

This is because bzrlib (and all subpackages) packed to one library.zip 
file, therefore plugin launchpad is also resides inside this zip file. 
And current implementation of plugin load mechanism is unable to look 
into zip and load module from zip.

This bug is here from 0.8 release (when launchpad and bzr.exe was 
introduced).

I think this need to be fixed, but it's not trivial right now (for me), 
so I think it should be fixed for 0.13.

--
Alexander