Merge the r1489114 group from trunk:

 * r1489114, r1489116
   Require Serf 1.2.1.
   Justification:
     Serf 1.2.0 doesn't work where Digest authentication is in use.
     See http://subversion.tigris.org/issues/show_bug.cgi?id=4371 and
     https://code.google.com/p/serf/issues/detail?id=102 for details.
   Notes:
     This is a blocking issue.
   Votes:
     +1: cmpilato, gstein, ivan


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/1.8.x@1489698 13f79535-47bb-0310-9956-ffa450edef68
Merge r1489203 from trunk:

 * r1489203
   Fix a crash when the automatic merge API is called with unrelated source
   and target branches, other than by 'svn' which does an ancestry check
   before calling it.  Also affected svn_client_get_merging_summary().
   Justification:
     It's a crash. The fix is a straightforward check.
   Notes:
     Tested as in the email: by temporarily removing the check at
     merge-cmd.c:109 and trying a mismatched automatic merge.
   Votes:
     +1: julianfoad, ivan, pburba


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/1.8.x@1489699 13f79535-47bb-0310-9956-ffa450edef68
Merge r1488878 from trunk:

 * r1488878
   Don't leave return value uninitialised.
   Justification:
     Possible SEGV when using legacy status API.
   Votes:
     +1: philip, brane, rhuijben


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/1.8.x@1489700 13f79535-47bb-0310-9956-ffa450edef68
Merge r1488425 from trunk:

 * r1488425
   Fix issue 4369, poor serf error message for commit with stolen locks.
   Justification:
     Confusing to user and a regression from 1.7/neon.
   Votes:
     +1: philip, rhuijben, ivan
     +0: danielsh


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/1.8.x@1489701 13f79535-47bb-0310-9956-ffa450edef68
Merge r1488183 from trunk:

 * r1488183
   Check target WC for mixed revisions, local modifications and switched
   subtrees before contacting server for merge calculations.
   Justification:
     Merge calculations can easy take 10 seconds over WAN, while mixed
     revisions working copy are common. Small fix.
   Votes:
     +1: ivan, philip, julianfoad


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/1.8.x@1489702 13f79535-47bb-0310-9956-ffa450edef68