Shell: Use sys.executable in doctest
Shell: Use sys.executable in doctest

... instead of python which is not availabe on Linux systems without
having Python 2 installed (Python 3 is called python3 on command
line). Now Python 2 is not necessary for the modified doctest
to execute.

coala/coala,jayvdb/coala,coala-analyzer/coala,SanketDG/coala,coala-analyzer/coala,coala/coala,coala-analyzer/coala,SanketDG/coala,jayvdb/coala,SanketDG/coala,jayvdb/coala,coala/coala