It is true, little or no damage will result.
Simply pump all you can out, replace it with as much diesel as possible to dilute the gas out, change the filter and prefil the new one with diesel. You can try using the hand pump to circulate as much diesel into the system as possible before starting.
Even if any damage did occur, theres nothing you can do about it but wait for the part to fail and replace it. Most likely the car will live happily ever after.
2003 Jetta Wagon TDI 145,000MI
1999.5 Jetta TDI 287,000MI
2001 Suzuki SV650S 26,000MI
2008 Yamaha Vino 125 11,000MI