Open 1.8.x backport branch for r1554978.

git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/1.8.x-r1554978@1555500 13f79535-47bb-0310-9956-ffa450edef68
Merged r1554978 from /trunk and resolved the usual FSFS reorg conflict.

git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/1.8.x-r1554978@1555514 13f79535-47bb-0310-9956-ffa450edef68
Merge r1555499 from trunk:

 * r1555499
   Release internal FS objects when closing a commit editor.
   Justification:
     close_edit() and abort_edit() are supposed to do a complete internal
     cleanup - albeit the API docs are slightly fuzzy about that.
   Votes:
     +1: stefan2, rhuijben, breser


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/1.8.x@1565076 13f79535-47bb-0310-9956-ffa450edef68
Merge the 1.8.x-r1554978 branch:

 * r1554978
   In FSFS, svn_fs_get_file_delta_stream shall return strictly the delta requested.
   Justification:
     The delta stream returned here has been valid (a self-delta is a valid
     txdelta against *any* source) but it may not strictly be what the user
     requested.  As a side effect, this will produce smaller deltified dumps.
   Branch:
     ^/subversion/branches/1.8.x-r1554978
   Votes:
     +1: stefan2, rhuijben, breser


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/1.8.x@1565077 13f79535-47bb-0310-9956-ffa450edef68