code fails on scons master with python3

This code is failing:
        RPATH = [Literal(':'.join([ORIGIN + x for x in 
':'.join([MKLPATH]).split(':')]))]

with error:
scons: *** [mkl.cpython-35m-x86_64-linux-gnu.so] TypeError `unhashable type: 
'Literal'' trying to evaluate `${_concat(RPATHPREFIX, RPATH, RPATHSUFFIX, 
__env__)}'

But this code succeeds on my own (old) port of scons to python3