Fork Join Consistency

Same as Fork Consistency when server is correct.

Fork resolution (join) when servers misbehaviour detected.

updating:

c1:  -<c1_u1>----------------------------------<c1_u2>----------------------------------

c2:  ---------------------<c2_u1>--------------------------------------<c2_u2>----------

ordering:
                                      /--------(c1_u2)----------------------------------
s:  -(c1_u1)--------------(c2_u1)----<
                                      \--------------------------------(c2_u2)----------

fork seen as concurrent updates to different servers:

s1:-(c1_u1)-------------(c2_u1)-------------------------(c1_u2)-------------------------

s2:-(c1_u1)-------------(c2_u1)-------------------------(c2_u2)-------------------------