spack flake8 should exempt line-wrapped directives (#3990)
spack flake8 should exempt line-wrapped directives (#3990)

- Omit final paren from regular expressions in cmd/flake8.py
- Allows long directives to be exempted even if they are wrapped.
TheTimmy/spack,krafczyk/spack,matthiasdiener/spack,krafczyk/spack,krafczyk/spack,lgarren/spack,lgarren/spack,TheTimmy/spack,LLNL/spack,matthiasdiener/spack,tmerrick1/spack,matthiasdiener/spack,mfherbst/spack,iulian787/spack,skosukhin/spack,EmreAtes/spack,tmerrick1/spack,krafczyk/spack,skosukhin/spack,iulian787/spack,tmerrick1/spack,TheTimmy/spack,EmreAtes/spack,TheTimmy/spack,skosukhin/spack,EmreAtes/spack,tmerrick1/spack,LLNL/spack,LLNL/spack,TheTimmy/spack,lgarren/spack,EmreAtes/spack,EmreAtes/spack,iulian787/spack,LLNL/spack,LLNL/spack,matthiasdiener/spack,mfherbst/spack,lgarren/spack,skosukhin/spack,krafczyk/spack,lgarren/spack,iulian787/spack,iulian787/spack,mfherbst/spack,mfherbst/spack,skosukhin/spack,matthiasdiener/spack,tmerrick1/spack,mfherbst/spack