Indeed now that stored procedures CALL is not binlogged, but instead the invoked substatements are,
the restrictions applied by log-bin-trust-routine-creators=0 are superfluous for procedures.
They still need to apply to functions where function calls are written to the binlog (for example as "DO myfunc(3)").
We rename the variable to log-bin-trust-function-creators but allow the old name until some future version (and issue a warning if old name is used).