Uniform way to launch bzr in subprocess.

[INADA Naoki]

Hi, all.
Recently, qbzr and TortoiseBZR faces a bug relates how to launch a bzr
subprocess.
(see https://bugs.launchpad.net/tortoisebzr/+bug/641557)

qbzr 0.19.1 and before uses sys.argv[0] to executable and
tbzrcommand.exe replaces it.
Bazaar Explorer also finds executable sys.argv[0] it's own way.

What's the correct way to call bzr plugin from application that is not bzr and
bzr plugins calls bzr as subprocess?

-- 
INADA Naoki  <songofacandy at gmail.com>