Reimplement `interruptable_popen` to handle non-UTF8 output.

analysis/tasks/Absolute.py

analysis/tasks/AddStatunc.py

analysis/tasks/Combine.py

analysis/tasks/CopyFastWarm.py

analysis/tasks/CopyMergeFastWarm.py

analysis/tasks/CopyRewarmup.py

analysis/tasks/CopyTables.py

analysis/tasks/CopyWarmup.py

analysis/tasks/DataComparison.py

analysis/tasks/FastProd.py

analysis/tasks/FastWarm.py

analysis/tasks/FnloCppread.py

analysis/tasks/FnloCppreadFinal.py

analysis/tasks/KfacComparison.py

analysis/tasks/MergeFastProd.py

analysis/tasks/MergeFastWarm.py

analysis/tasks/MergeFinal.py

analysis/tasks/MergedGridClosure.py

analysis/tasks/MultiGridClosure.py

analysis/tasks/PdfUncertainty.py