9.5.2: "sql" as reserved word?

Hello,

This query is working in 9.4.x, but not in 9.5.2:

select 'x' sql;

ERROR: syntax error at or near "sql"
LINE 1: select 'x' sql;

Is this expected or a known issue?
I could neither find any hint about it in the incompatibility list of the 9.5 release notes,
nor is "sql" listed as reserved keyword.

best regards,

Marc Mamin