score:4
The relevant rule is article 6.1 of the Schengen Borders Code:
For intended stays on the territory of the Member States of a duration of no more than 90 days in any 180-day period, which entails considering the 180-day period preceding each day of stay, the entry conditions for third-country nationals shall be the following:
(a) they are in possession of a valid travel document entitling the holder to cross the border satisfying the following criteria:
(i) its validity shall extend at least three months after the intended date of departure from the territory of the Member States. In a justified case of emergency, this obligation may be waived;
(ii) [...]
(b)-(e) [...]
This is actual EU legislation. It leaves some room for border guards to declare that a "justified case of emergency" exists. However I would expect that to be an extremely uphill battle in case of a plain pleasure visit.