The OOPS did end up loading (eventually) for me with:
  Fault: <Fault -1: 'OOPS-394216d625e87559cda9d8b92d70b90f'>

    Traceback (most recent call last):
  File "/srv/bazaar.launchpad.net/production/codehosting2-rev-15505/lib/lp/services/twistedsupport/__init__.py", line 139, in wrapped
    return func(*args, **kwargs)
  File "/srv/bazaar.launchpad.net/production/codehosting2-rev-15505/lib/lp/codehosting/vfs/branchfs.py", line 686, in got_path_info
    data['id'], **info)
  File "/srv/bazaar.launchpad.net/production/codehosting2-rev-15505/lib/lp/codehosting/vfs/branchfsclient.py", line 123, in branchChanged
    repository_string)
  File "/srv/bazaar.launchpad.net/production/codehosting2-rev-15505/lib/lp/services/twistedsupport/xmlrpc.py", line 50, in callRemote
    method_name, *args, **kwargs)
--- <exception caught here> ---
  File "/srv/bazaar.launchpad.net/production/codehosting2-rev-15505/eggs/Twisted-11.1.0-py2.6-linux-x86_64.egg/twisted/internet/defer.py", line 134, in maybeDeferred
    result = f(*args, **kw)
  File "/srv/bazaar.launchpad.net/production/codehosting2-rev-15505/lib/lp/services/twistedsupport/xmlrpc.py", line 35, in callRemote
    return getattr(self._proxy, method_name)(*args, **kwargs)
  File "/usr/lib/python2.6/xmlrpclib.py", line 1199, in __call__
    return self.__send(self.__name, args)
  File "/usr/lib/python2.6/xmlrpclib.py", line 1489, in __request
    verbose=self.__verbose
  File "/usr/lib/python2.6/xmlrpclib.py", line 1253, in request
    return self._parse_response(h.getfile(), sock)
  File "/usr/lib/python2.6/xmlrpclib.py", line 1392, in _parse_response
    return u.close()
  File "/usr/lib/python2.6/xmlrpclib.py", line 838, in close
    raise Fault(**self._stack[0])
xmlrpclib.Fault: <Fault -1: 'OOPS-394216d625e87559cda9d8b92d70b90f'>

And following that OOPS I get:
RequestExpired: request expired.

    Traceback (most recent call last):
  Module zope.publisher.publish, line 134, in publish
    result = publication.callObject(request, obj)
  Module lp.services.webapp.publication, line 458, in callObject
    return mapply(ob, request.getPositionalArguments(), request)
  Module zope.publisher.publish, line 109, in mapply
    return debug_call(obj, args)
   - __traceback_info__: <security proxied zope.app.publisher.xmlrpc.metaconfigure.CodehostingAPI instance at 0x14871ad0>
  Module zope.publisher.publish, line 115, in debug_call
    return obj(*args)
  Module lp.code.xmlrpc.codehosting, line 289, in branchChanged
    return run_with_login(login_id, branch_changed)
  Module lp.code.xmlrpc.codehosting, line 111, in run_with_login
    requester = getUtility(IPersonSet).get(login_id)
  Module lp.registry.model.person, line 3602, in get
    return Person.get(personid)
  Module storm.sqlobject, line 321, in get
    obj = store.get(cls, id)
  Module storm.store, line 178, in get
    result = self._connection.execute(select)
  Module storm.databases.postgres, line 266, in execute
    return Connection.execute(self, statement, params, noresult)
  Module storm.database, line 238, in execute
    raw_cursor = self.raw_execute(statement, params)
  Module storm.databases.postgres, line 276, in raw_execute
    return Connection.raw_execute(self, statement, params)
  Module storm.database, line 316, in raw_execute
    statement, params or ())
  Module storm.database, line 371, in _check_disconnect
    return function(*args, **kwargs)
  Module storm.tracer, line 216, in trace
    attr(*args, **kwargs)
  Module lp.services.webapp.adapter, line 609, in connection_raw_execute
    if self.get_remaining_time() is None:
  Module lp.services.webapp.adapter, line 646, in get_remaining_time
    return get_request_remaining_seconds()
  Module lp.services.webapp.adapter, line 352, in get_request_remaining_seconds
    raise RequestExpired('request expired.')
RequestExpired: request expired.

Which sounds like we just got a disconnect in the middle.

It is possible that just re-trying your commit will work this time. Offhand, it looks like someone was restarting a service while you were doing the commit.