In the merge code, never leave a repo_location_t's repository root fields as NULL.
In the merge code, never leave a repo_location_t's repository root fields as
NULL.

* subversion/libsvn_client/merge.c
  (repo_location_create): Don't allow the incoming repository root fields to
    be NULL.
  (combine_range_with_segments): Take a location instead of just a URL, and
    use it to fill in the repository root fields.
  (find_base_on_source): Fill in the repository root fields.
  (make_conflict_versions, normalize_merge_sources_internal): Use the stored
    root URL instead of asking the session.

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion