Switched conditional operator to or

Found this to be slightly faster and it catches values like an empty
string as well.

Change-Id: I31669bf17dbe8330db48b5d03d6e19ac9668a259
Reviewed-on: http://review.couchbase.org/23682
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>