For Germany:
I had an appointment today with a lawyer for capital market laws.
He wasn't deeply involved with the situation and former developments (such as the Google split in the past), but confirms that it
should not be a taxable event based on German laws (§ 20 Absatz 4a Satz 5 EStG). This is also visible in following information from the
Federal Finance Ministry under Number 111.
Furthermore, he advised me to contact my local tax authority with a "Verbindliche Auskunft" (information request), which they have to answer. I am waiting on further information from the lawyer,
but found this online.
Nevertheless, even so the law situation points into the direction of no taxes, some German based broker might deduct taxes as just in case it would be a taxable event, as explained by the Federal Finance Ministry in this recent
"Referentenentwurf" on page 88.
Overall, I came to the conclusion that I won't sell any shares beforehand. If it would be a taxable event, I am planning to take legal steps.
Of course, this is no tax advise in any kind.