[Buildbot-devel] Twisted exception with Buildbot 0.8.5 + Mercurial hook

[Bob Hood]

I recently migrated our Buildbot 0.8.5 + Twisted 12.0.0 + zope 3.6.1 to a new
Debian Linux instance that is running x64 and Python 2.7.3.  We are using
Mercurial with the changegroup.buildbot hook, i.e.:

    [hooks]
    changegroup.buildbot = python:buildbot.changes.hgbuildbot.hook

I'm now getting an exception in Twisted that I wasn't getting before whenever
a change is pushed to the Mercurial server:

pushing to https://...
searching for changes
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 1 changesets with 1 changes to 1 files
remote: Unhandled Error
remote: Traceback (most recent call last):
remote:   File
"/usr/local/lib/python2.7/dist-packages/Twisted-12.0.0-py2.7-linux-x86_64.egg/twisted/internet/base.py",
line 413, in fireEvent
remote:     DeferredList(beforeResults).addCallback(self._continueFiring)
remote:   File
"/usr/local/lib/python2.7/dist-packages/Twisted-12.0.0-py2.7-linux-x86_64.egg/twisted/internet/defer.py",
line 301, in addCallback
remote:     callbackKeywords=kw)
remote:   File
"/usr/local/lib/python2.7/dist-packages/Twisted-12.0.0-py2.7-linux-x86_64.egg/twisted/internet/defer.py",
line 290, in addCallbacks
remote:     self._runCallbacks()
remote:   File
"/usr/local/lib/python2.7/dist-packages/Twisted-12.0.0-py2.7-linux-x86_64.egg/twisted/internet/defer.py",
line 551, in _runCallbacks
remote:     current.result = callback(current.result, *args, **kw)
remote: --- <exception caught here> ---
remote:   File
"/usr/local/lib/python2.7/dist-packages/Twisted-12.0.0-py2.7-linux-x86_64.egg/twisted/internet/base.py",
line 426, in _continueFiring
remote:     callable(*args, **kwargs)
remote:   File
"/usr/local/lib/python2.7/dist-packages/Twisted-12.0.0-py2.7-linux-x86_64.egg/twisted/internet/base.py",
line 1164, in _reallyStartRunning
remote:     self._handleSignals()
remote:   File
"/usr/local/lib/python2.7/dist-packages/Twisted-12.0.0-py2.7-linux-x86_64.egg/twisted/internet/posixbase.py",
line 298, in _handleSignals
remote:     self._childWaker.install()
remote:   File
"/usr/local/lib/python2.7/dist-packages/Twisted-12.0.0-py2.7-linux-x86_64.egg/twisted/internet/posixbase.py",
line 212, in install
remote:     _signals.installHandler(self.o)
remote:   File
"/usr/local/lib/python2.7/dist-packages/Twisted-12.0.0-py2.7-linux-x86_64.egg/twisted/internet/_signals.py",
line 132, in _installHandlerUsingSetWakeup
remote:     return set_wakeup_fd(fd)
remote: exceptions.ValueError: set_wakeup_fd only works in main thread
remote: rev 0e77c7bd37a38b14658eaa9e62bc0763723bde1b sent

Has anybody else experienced this before with Buildbot?  I'm rather stumped,
because these are the same versions of these packages that I used on the other
Linux and never saw these kinds of errors.

(No, I am not in a position to upgrade any of them, so please don't suggest it.)