Function r-value called more than once in multi-variable assignment

[PhilipRoman]

The removal of variable-length registers has caused a bug to appear (found on ir_refactor branch):

function f() print "Hit!"; return 1, 2, 3 end
local a, b, c, d = 0, f()

Expected output:

Hit!

Actual output:

Hit!
Hit!
Hit!