Make a backport branch for r1426762, issue #4283, a diff suffix problem.

git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/1.7.x-r1426762@1538732 13f79535-47bb-0310-9956-ffa450edef68
On the 1.7.x-r1426762 branch, backport r1426762 from trunk.

git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/1.7.x-r1426762@1538734 13f79535-47bb-0310-9956-ffa450edef68
Merge the 1.7.x-r1426762 branch:

 * r1426762
   Fix issue #4283, When the identical suffix starts at chunk boundary, "svn
   diff" produces incorrect diff.
   Justification:
     Without this patch the identical suffix might show up as an added or
     deleted suffix of a file.
   Branch:
     ^/subversion/branches/1.7.x-r1426762
   Votes:
     +1: rhuijben, jcorvel, julianfoad
     +0: stsp (doesn't compile, undefined reference to `svn_stringbuf_insert')
              (referring to r1426762 by itself without the branch)


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/1.7.x@1538860 13f79535-47bb-0310-9956-ffa450edef68