The answer might simply be: You can't.
Whether or no this is desirable could be debated, but having worked on a couple of these things in Mozilla/Firefox days, I think it is clear that someone (aka Apple) would create a browser location opener-thingie to do it this way.
Here's why I think this is Safari expected behavior:
The match you are looking is a match to a Bookmarks and History via the Title. The URL is being provided for your convenience (or if you come from a certain period of browser design and/or security orientation, its to mitigate more obvious versions of URL spoofing). It isn't trying to present TITLE PLUS URL... because if it were a mult-mode search /bookmarks+history / location interface, that would not make any sense. (You could argue it could support this, but that's yet-another input syntax, and a whole other round of feature development...)
The URL is not mean to be editable text in this context.
I do think there is a bug which could be either:
The auto-completion shouldn't be implied with a normal selection color, because you can't trigger completion to make the editable text appear in the location field. (Nor does cut and paste operate correctly on this string).
Best Answer
I have had the same issue happen to me, once (I also have the same laptop)....I just rebooted and it never happened again.
I'm unsure if it's even a machine/OS X issue or a scripting error.
Hopefully that solves your same problem.