Revision 1764565

Merge the 1.8.x-r1702299 branch:

 * r1702299, r1702300, r1702397, r1702407, r1702565
   Handle merging to local add as error instead of segfault.
   Justification:
     Segfault. User reported.
   Notes:
     r1702299 adds a testcase.
     r1702397 fixes the problem with automatic merge and updates the test.
     r1702565 fixes a quite similar segfault with --reintegrate merge.
     The other revisions are minor cleanup.
   Branch:
     ^/subversion/branches/1.8.x-r1702299
   Votes:
     +1: rhuijben, julianfoad, stefan2