Comment 8 for bug 235681

The version of python-launchpad-bugs in -proposed (0.2.30.1) fixes this bug for me.

[with 0.2.30]
In [1]: from launchpadbugs.connector import ConnectBug

In [2]: Bug = ConnectBug()

In [3]: Bug.authentication = "/home/markus/.mozilla/firefox/iy3ore6m.default/cookies.sqlite"

In [4]: b = Bug(234363)

In [5]: b.subscribers.add("thekorn")

In [6]: xmode
Exception reporting mode: Verbose

In [7]: xmode
Exception reporting mode: Plain

In [8]: b.commit()
------------------------------------------------------------
Traceback (most recent call last):
  File "<ipython console>", line 1, in <module>
  File "/usr/lib/python2.5/site-packages/launchpadbugs/html_bug.py", line 1268, in commit
    result = i.component.commit(force_changes, ignore_lp_errors)
  File "/usr/lib/python2.5/site-packages/launchpadbugs/html_bug.py", line 945, in commit
    self._add(i)
  File "/usr/lib/python2.5/site-packages/launchpadbugs/html_bug.py", line 959, in _add
    raise ValueError, "Unknown error while subscribe %s to %s" %(lplogin, url)
<type 'exceptions.ValueError'>: Unknown error while subscribe thekorn to https://bugs.edge.launchpad.net/buglog-data/+bug/234363/+addsubscriber

[with 0.2.30.1]
In [1]: from launchpadbugs.connector import ConnectBug

In [2]: Bug = ConnectBug()

In [3]: Bug.authentication = "/home/markus/.mozilla/firefox/iy3ore6m.default/cookies.sqlite"

In [4]: b = Bug(234363)

In [5]: b.subscribers.add("thekorn")

In [6]: xmode plain
Exception reporting mode: Plain

In [7]: b.commit()

In [8]: b = Bug(234363)

In [9]: b.subscr
b.subscribers b.subscribtions b.subscriptions

In [9]: b.subscribers
Out[9]: <Subscribers>

In [10]: print b.subscribers
set([<user dholbach (Daniel Holbach)>, <user thekorn (Markus Korn)>])

Markus