The HFS-style pathname shown is in exact correspondence to the Posix-style pathname. Both are relative pathnames: they refer to a subpath relative to the working directory.
http://en.wikipedia.org/wiki/Working_directory
Leading-colon means "relative path" and no-leading-colon means absolute in HFS-style. Leading-slash means "absolute path" and no-leading-slash means relative in Posix-style.
So if you removed the leading colon, you'd have a completely different meaning. It would correspond to "/Your/full/unix/path/here".