when trying to get attributes during acquisition.  For example, it was
common for acquisition to mask errors occuring when trying to load
object state from the database, since this is typically triggered by a
getattr call.  I wanted to do something like:

  try: foo.bar
  except AttributeError, v:
    if v != 'bar': raise # Bogus attribute error
    # keep looking up the acquisition tree

Unfortunately, this fails because v is (sometimes) an
instance, not a string.

For now, we'll check for attribute errors, but ingore the values.