ckarlof was able to reproduce Rob's result -- but not Vlad's.
Bug 1549129 Comment 4 Edit History
Note: The actual edited comment in the bug view page will always show the original commenter’s name and original timestamp.
ckarlof was able to reproduce Vlad's result.
ckarlof was able to reproduce Vlad's result. After applying 66.0.4 build 3, the Unsupported extension was restored (and enabled).
ckarlof was able to reproduce Vlad's result -- as far as getting into the state with epub being unsupported after a restart on 66.0.3. After applying 66.0.4 build 3, the Unsupported extension was restored (and enabled).