Same story as always: You did the right thing -- you gave these people proper notice, and agreed to postpone your exit until the release date on your current p

Same story as always: You did the right thing -- you gave these people proper notice, and agreed to postpone your exit until the release date on your current project (i.e. already making a significant concession to your current employer, at the expense of your next problem). After which your current company apparently screwed up (as they seem to be in the habit of doing), and botched the release date. But once again: you did the right thing, already. Therefore, at this point, you owe them nothing. You certainly don't "owe" it to them to discount your next employer any further -- and not only that, it would, clearly, be unprofessional for you to do so (or for your current employer to ask you to do so). And not only that -- your next employer might very well (and very understandably) get fold feet, think "this guy has attachment / commitment" issues -- and withdraw their offer. Employers do this all the time, even without a good reason, or any reason actually. But in this case, you'd be giving them an awfully tempting reason. So please don't do that.