Remove python 2.6-incompatible format expression.
Remove python 2.6-incompatible format expression.

matthiasdiener/spack,tmerrick1/spack,LLNL/spack,krafczyk/spack,lgarren/spack,LLNL/spack,EmreAtes/spack,matthiasdiener/spack,tmerrick1/spack,TheTimmy/spack,krafczyk/spack,TheTimmy/spack,skosukhin/spack,iulian787/spack,skosukhin/spack,lgarren/spack,lgarren/spack,skosukhin/spack,tmerrick1/spack,skosukhin/spack,mfherbst/spack,iulian787/spack,LLNL/spack,iulian787/spack,tmerrick1/spack,matthiasdiener/spack,lgarren/spack,EmreAtes/spack,mfherbst/spack,matthiasdiener/spack,iulian787/spack,EmreAtes/spack,tmerrick1/spack,skosukhin/spack,mfherbst/spack,mfherbst/spack,TheTimmy/spack,krafczyk/spack,LLNL/spack,iulian787/spack,TheTimmy/spack,lgarren/spack,EmreAtes/spack,matthiasdiener/spack,krafczyk/spack,mfherbst/spack,TheTimmy/spack,LLNL/spack,krafczyk/spack,EmreAtes/spack