Reported by ragb on 2012-10-13 11:05
The add-on translation machhinery can not be used from installTasks module, due to the add-on beeing not present in available add-ons on installTasks.onInstall execute time. This means that the current add-on can not be found, so addonHandler.initTranslation can not instanciate the corrent gettext translation.

Attached patch solves this issue, moving the insertion to addonHandler._availableAddons before installTasks.onInstall execution. I can commit if agreed.