Catching error caused by `source` closing file argument before reading from it.

Just added the same lines that isaacs has in completion.js to catch the EPIPE error caused by using console.log or process.stdout.write in a subshell used for process substitution.

Near as I can tell the only way to make this work on OS X is to ask the user to:

    $ pkgname completion > /usr/local/etc/bash_completion.d/pkgname.bash
    $ echo "source /usr/local/etc/bash_completion.d/pkgname.bash" >> .bashrc

I'm trying to find out if there is an alternate bash syntax for use in .bashrc that will keep the file descriptor open long enough to `source` from it.