vapor barrier behind wall

Hi everyone; first time up.
I am about to help someone install a shower that was completely destroyed by incorrectly installed recessed soap and shampoo dispensers. When he ripped out the tile and backerboard, the moisture barrier is ripped. It also the only thing standing between the shower and some siding! That's it..no plywood..nothing else..just a moisture barrier on some 2bys and the house. Since the barrier has a couple of rips, is there a way to patch it with some special bonding agent so that I can patch the holes? I realize the ideal thing would be to remove the siding and re-install a new barrier but if I can do a decent patch it would save us both a lot of work. Any ideas? Thanks in advance.