Made spec hashes immutable once concrete
Made spec hashes immutable once concrete

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