log windows closes instantly when calling from a virtual repository

[André Bachmann]

Bazaar 2.3.3-3 on Win7 32 Bit:

1. I open a virtual repository in my Bazaar Explorer.
2. I click on 'Log'.
3. The log windows closes itself instantly.

If i look in my .bzr.log, I see the reason - it's not a branch (of course):

===========================================================
Fri 2011-05-27 12:16:37 +0200
0.073 bazaar version: 2.3.3
0.073 bzr arguments: [u'qlog', u'C:/BZR-Repos']
0.102 looking for plugins in C:/Users/abachmann/AppData/Roaming/bazaar/2.0/plugins
0.103 looking for plugins in C:/Program Files/Bazaar/plugins
0.285 encoding stdout as osutils.get_user_encoding() 'cp1252'
0.493 Traceback (most recent call last):
  File "C:/Program Files/Bazaar/plugins\qbzr\lib\trace.py", line 321, in reports_exception_decorate
  File "C:/Program Files/Bazaar/plugins\qbzr\lib\log.py", line 242, in load
  File "C:/Program Files/Bazaar/plugins\qbzr\lib\log.py", line 284, in get_branches_and_file_ids
  File "bzrlib\bzrdir.pyo", line 837, in open_containing_tree_branch_or_repository
  File "bzrlib\bzrdir.pyo", line 762, in open_containing
  File "bzrlib\bzrdir.pyo", line 794, in open_containing_from_transport
NotBranchError: Not a branch: "C:/BZR-Repos/".

0.506 return code 0
===========================================================

An error message or simply a deactivated Log button while in a virtual repository would be very helpful to avoid confusion. Only an opening and instantly closing window isn't very helpful.

[Alexander Belchenko (bialix)]

IThat's because bzr-explorer calls qlog and qlog got NotBranchError, prints it to the stdout and exit. And because stdout with explorer may not exists at all, we have this issue.

I think we can add --ui-mode or something similar to qlog and other browse commands to make sure qbzr don't print error messages to stdout but shows GUI error dialog instead.