I haven't read the contract, but the way i see it, you don't have to repay anything. You simply have to stay the amount of time stipulated, or pay a pro rate of the mentioned sum. So even if you fail the upgrade, no payment or loss of salary involved, unless you leave before time.
I don't particularly such tactics, they only blatantly expose the incompetence of the management, however let's keep it in a reasonable context. Even DECs were bonded since 2003 and no one complained there!