Classical registers are set incorrectly after being Permuted

[perlinm]

This example:

import pecos.slr
prog = pecos.slr.Main(
    a := pecos.slr.CReg("a", size=1),
    b := pecos.slr.CReg("b", size=1),
    pecos.slr.Permute(a, b),
    a[0].set(1),
    a.set(1),
)
print(prog.qasm())

prints

...
// Permuting: b[0] -> a[0]
b[0] = 1;
a = 1;

This behavior will cause problems when using the values of classical registers that have been permuted.