tests/test-gendoc-it.t

httppeer: make __del__ access to self.urlopener more safe

Some errors could in some cases show unfortunate scary and confusing warnings
from the httppeer delstructors:

  abort: nodename nor servname provided, or not known
  Exception AttributeError: "'httpspeer' object has no attribute 'urlopener'" in <bound method httpspeer.__del__ of <mercurial.httppeer.httpspeer object at 0x106e1f5d0>> ignored```

To mute that, take 7b15dd9125b3 to the next level and use getattr in __del__.

#require docutils gettext

  $ $TESTDIR/check-gendoc it
  checking for parse errors