flake8: make entire repository pass spack flake8 -a

- Fix trailing whitespace missed by the bug described in #12755.

- Fix other style issues that have crept in over time (this can happen
  when flake8 adds new checks with new versions)

var/spack/repos/builtin/packages/blasr/package.py

@@ -13,7 +13,7 @@ class Blasr(Package):
     homepage = "https://github.com/PacificBiosciences/blasr/wiki"
     url      = "https://github.com/PacificBiosciences/blasr/archive/5.3.1.tar.gz"
 
-    version('5.3.1', '53c93f499aa4bc10781c87bafc33df2a') 
+    version('5.3.1', '53c93f499aa4bc10781c87bafc33df2a')
 
     depends_on('ncurses')
     depends_on('hdf5+cxx@1.8.12:1.8.99')