Yup grabbing the first release with https://hg.mozilla.org/mozilla-central/rev/449fb0bd623f and calling `removeAllSince` directly results in UNKNOWN.
Bug 1557153 Comment 52 Edit History
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Yup grabbing the first release with https://hg.mozilla.org/mozilla-central/rev/449fb0bd623f -> https://archive.mozilla.org/pub/firefox/nightly/2014/09/2014-09-16-03-02-04-mozilla-central/ and calling `removeAllSince` directly results in UNKNOWN.