Google App Engine channel code fails in production with javascript "Cannot read property 'removeEventListener' of undefined " error

Google App Engine channel code fails in production with javascript "Cannot
read property 'removeEventListener' of undefined " error

I have code that used to work and still works with the latest SDK 1.8.3
However in production it does not work any more. It fails right here:
ch = new goog.appengine.Channel(token);
ch.open(); <--- this never returns
The browser debugger shows the stacktrace below. The channek.js code from
production https://talkgadget.google.com/talkgadget/channel.js
Uncaught TypeError: Cannot read property 'removeEventListener' of
undefined [VM] channel.js (18280):22
Qb [VM] channel.js (18280):22
cb [VM] channel.js (18280):14
g.Ma [VM] channel.js (18280):30
Zd [VM] channel.js (18280):88
ae [VM] channel.js (18280):87
$ [VM] channel.js (18280):95
ge.open [VM] channel.js (18280):100
reset 062a630fa51c7bd829554631f0939936-school_swapp.js:1
(anonymous function)
In the case of the SDK I also see some random javascript stack traces that
look like the one below but with the SDK the code works as expected. I
mention this for completeness in case somebody can spot the issue.
Uncaught TypeError: Cannot call method 'markAsRemoved' of undefined
jsapi:3069
goog.events.ListenerMap.removeAll jsapi:3069
goog.events.EventTarget.removeAllListeners jsapi:3159
goog.events.EventTarget.disposeInternal jsapi:3142
goog.net.XhrIo.disposeInternal jsapi:4915
goog.Disposable.dispose jsapi:2538
goog.net.XhrIo.cleanupSend_ jsapi:4841
goog.events.EventTarget.fireListeners jsapi:3171
goog.events.EventTarget.dispatchEventInternal_ jsapi:3207
goog.events.EventTarget.dispatchEvent jsapi:3138
goog.net.XhrIo.cleanUpXhr_ jsapi:4955
goog.net.XhrIo.onReadyStateChangeHelper_ jsapi:4943
goog.net.XhrIo.onReadyStateChangeEntryPoint_ jsapi:4927
goog.net.XhrIo.onReadyStateChange_