Drop superfluous handling of bash and zsh completion files
    
    /usr/share/bash-completion/completions is owned by the ubiquitous
    filesystem package (and bash-completion). This package shouldn't own it.
    
    /usr/share/bash-completion/completions/hg is already installed by
    setup.py . zsh is also installed by setup.py, but as _hg . List both
    files with the right macros and explicitly, even though it temporarily
    will list the files twice since they also are in the file list.
    
    This change was isolated and documented (and obfuscated?) by Mads Kiilerich.