Right, as Gregory said.

From the backtrace he send me, it seems that the following happens:

from mercurial import hg # in Trac, with demandimport disabled at that point
import localrepo, ... # in mercurial/hg.py
import os, revlog, time, util, extensions, ... # in mercurial/localrepo.py
# ...
class bundlerepository(localrepo.localrepository): # in mercurial/bundlerepo.py
-> AttributeError: 'module' object has no attribute 'localrepository'

Any hint about a workaround I could apply in TracMercurial to make it compatible
with the released Mercurial 0.9.4?