ExtOpenScad Let block of function definition gets wrong arguments

[acoth]

Accessing function arguments normally works as expected, but within a let block, it gets the previous argument instead.
Simple example:
function foo(a,b,c) = let(output=b) [output,b]; echo(foo(1,2,3));

returns [1.0,2.0] instead of the expected [2.0,2.0]

[lepsa]

@julialongtin I think that this can be closed now.