I've definitely done it. G-string on my Les Paul bass broke above the nut, just below the tuning peg post. Unwound the surplus (of which there was more than enough, since the Gib is short scale), tied a knot, rewound, finished the gig (went to bed, got up, went to the music store, and bought two sets of strings).
I can't say I have done it a lot of times, though.
R.