I don't know what bike you have, but the basic servo system on the R1150GS has a limited linked brake system.
The front brake operates both the front and rear brakes proportionally. The rear brake pedal only operates the rear brake. So with a rear brake pipe failure there isn't much you can do as operating either lever operates the rear brake.
What you could try doing as the pipe is already knackered, is try crimping the solid pipe flat, if you do it in several places along the pipe you may manage to block off the fluid, in which case you should be OK to ride it, but with caution as you would only have a front brake, and without the balanced braking of the servo system, you may find the front brake a bit harsh.
Ian