Fixed in r3326 (I think). Commit message:

translator:
* We now detect conditions that violate mutexes in a way that is not obvious
  from the default "partial encoding" (where facts that belong to several mutex
  groups are only represented in one SAS variable). This fixes translator crashes
  reported in issue34 (e.g. pipesworld-notankage #21).
* The bug fix requires that we always need to compute the "full encoding"
  (= all mutexes) in addition to the partial encoding, so we might as well write
  the all.groups file. Hence, option WRITE_ALL_MUTEXES is gone; it is now always
  enabled.
* This also fixes a long-standing issue with LAMA's translator that prevented
  us from setting ALLOW_CONFLICTING_EFFECTS to True, so ALLOW_CONFLICTING_EFFECTS
  is now set to True. (For more information, see the "Note" at the bottom of
  previous revisions of translate.py that mentions "on(a,a)" in blocksworld.)

The new translator fails with a "Conflicting add effects?" assertion on some
inputs on which the old one used to work:

  * pipesworld-notankage #21-50
  * pipesworld-tankage #21-25, #29, #31, #33-36, #39-40, #47-50