A:
111
222
222
55555
66666

B:
111
222
222MM
55555
66666
8888888

patchfile:
*** A
--- B
***************
*** 1,5 ****
  111
  222
! 222
  55555
  66666
--- 1,6 ----
  111
  222
! 222MM
  55555
  66666
+ 8888888

What to do? 
patch -p0 < patchfile #changes A

Solution:
--- /dev/null
+++ ./B

cp A B
patch -p1 < patchfile