On the fsfs-format7 branch:  fix a runtime complexity issue with reading
strings from a string table.  When creating the packed string, we need
to eliminate strings from the copy chain if they don't contribute to the
content of the string being reconstructed. 

* subversion/libsvn_fs_fs/string_table.c
  (create_table): skip strings that have a longer prefix than the current


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/fsfs-format7@1477180 13f79535-47bb-0310-9956-ffa450edef68