Replacing "apple hardware test" with "apple diagnostics" According to this article, holding down the "D" key while my MacBookPro11,3 boots should bring up "Apple Diagnostics".  However, "Apple Hardware Test" comes up instead.  When I try to run in, it fails, saying my hardware is not supported.

How do I replace the "Apple Hardware Test" firmware program with the "Apple Diagnostics" firmware program?

Some more background: This is a new macbook pro, and I copied the hard drive from my old one using disk utility.  After the transfer, the laptop worked fine, but would not boot into recovery mode-- holding down option at startup and selecting the recovery drive yielded a grey screen with a white, cross-out circle in the middle.  Re-downloading and re-installing Mavericks fixed this problem.  I can now boot into recovery mode, but I still have the problem described above.

Please do not answer this question if you don't understand the difference between "Apple Hardware Test" and "Apple Diagnostics."  Linking me to Apple support and pointing out that "Apple Diagnostics" replaced "Apple Hardware Test" in mid-2013 (as the 2 current answers have done) does not answer my question.
So you didn't write this much in your original post but I am going out on a limb and gonna say that the AHT that boots doesn't work on your Retina MBP.

The only way to get the file back is reinstall the OS via internet recovery but if the /System/Library/CoreServices/.diagnostics folder is there then I would wager a small bet that internet recovery won't put Apple Diagnostics on the drive. 

You can test this by deleting the current folder on your MacBook Pro and then trying internet recovery. OR (I'd first recommend this) you could start your computer into Internet Recovery and reinstall the OS on an external drive. Once the install is done just copy over the aforementioned .diagnostics folder and then move it onto your MacBook Pro's internal drive.

All the best and much fun ahead! (Please give internet recovery 1-2 hours depending on your internet connection and ethernet is highly encouraged)