bzr commands sometimes fail with "ERROR: not well-formed (invalid token)"

I have a c++ project with many apps sharing a common code basis, with many symbolic links (I try to pint out what can be different).
When I initialize bazaar, bzr check and any utility that tries to revert to any previous commit fails.
The same thing with a "fake" code tree works well.

This is the not working:

root@darkstar:/opt/ezechiele# rm -Rf /root/.bzr.log /root/.bazaar/ .bzr/
root@darkstar:/opt/ezechiele# bzr init
root@darkstar:/opt/ezechiele# bzr add
[...]
root@darkstar:/opt/ezechiele# bzr commit -m "initial commit"
[...]
Committed revision 1.
root@darkstar:/opt/ezechiele# bzr check
Checking working tree at 'file:///opt/ezechiele/'.
bzr: ERROR: not well-formed (invalid token): line 10892, column 74
root@darkstar:/opt/ezechiele# touch newfile.txt
root@darkstar:/opt/ezechiele# bzr status
unknown:
  newfile.txt
root@darkstar:/opt/ezechiele# bzr add newfile.txt
added newfile.txt
root@darkstar:/opt/ezechiele# bzr revert
bzr: ERROR: not well-formed (invalid token): line 10892, column 74
root@darkstar:/opt/ezechiele#

And this is the working:

root@darkstar:/opt# mkdir bzr_working
root@darkstar:/opt# cd bzr_working/
root@darkstar:/opt/bzr_working# touch work1.txt
root@darkstar:/opt/bzr_working# bzr init
root@darkstar:/opt/bzr_working# bzr add
added work1.txt
root@darkstar:/opt/bzr_working# bzr commit -m 'one'
Committing to: /opt/bzr_working/
added work1.txt
Committed revision 1.
root@darkstar:/opt/bzr_working# echo "xxx" > work1.txt
root@darkstar:/opt/bzr_working# bzr check
Checking working tree at 'file:///opt/bzr_working/'.
Checking repository at 'file:///opt/bzr_working/'.
checked repository <bzrlib.transport.local.LocalTransport url=file:///opt/bzr_working/> format <RepositoryFormatKnitPack1>
     1 revisions
     1 file-ids
     1 unique file texts
     0 repeated file texts
     0 unreferenced text versions
Checking branch at 'file:///opt/bzr_working/'.
checked branch file:///opt/bzr_working/ format Bazaar Branch Format 6 (bzr 0.15)
root@darkstar:/opt/bzr_working# bzr status
modified:
  work1.txt
root@darkstar:/opt/bzr_working# bzr revert
 M work1.txt

I use slackware-current.
I upgraded python to the last version available on slackware repos.
I tried with bazaar version 1.5, 1.6 (the last available), and the I compiled myself the 1.6.1.
No changes in the errors.
Thank you for the help.