Avoided COMP_WORDBREAKS modification

Modifying COMP_WORDBREAKS breaks ssh/scp completions (scp host:<Tab>
shrinks to scp /home/dir/ without the host part for example).  Found a
good answer (http://stackoverflow.com/a/12495480/390044) for this
problem, and simply applied the knowledge here.
Made variables local, cleaned up whitespaces
Merge commit '14468d73a988f7ad4d89b2be69ea5888c6e07029'