set_var.cc:
variables.result
variables.test

  Bug #10904 Illegal mix of collations between a system variable and a constant
  Changing coercibility of system variables to SYSCONST,
  to be the same with USER(), DATABASE(), etc.


sql/item_func.cc:
  Bug #10904 Illegal mix of collations between a system variable and a constant
  Changing coercibility of system variables to SYSCONST
  To be the same with USER(), DATABASE(), etc.