Following up on the explicit 'svn upgrade' requirement, reinstate the option of
opening a wc.db without upgrading for the upgrade process itself. This allows the
upgrade code to use a limited subset of the wc_db api to avoid having to
reimplement code just for upgrades.

* subversion/libsvn_wc/upgrade.c
  (bump_to_30): Obtain wc_db without upgrading to allow creating conflicts.

* subversion/libsvn_wc/wc_db.c
  (svn_wc__db_to_relpath,
   svn_wc__db_from_relpath,
   svn_wc__db_get_wcroot): Apply the same check for wcroots using a new macro.

* subversion/libsvn_wc/wc_db.h
  (svn_wc__db_open): Rename argument. Update documentation.
  (svn_wc__db_to_relpath
   svn_wc__db_from_relpath,
   svn_wc__db_get_wcroot): Document non-upgraded compatibility.

* subversion/libsvn_wc/wc_db_private.h
  (svn_wc__db_t):  Remove auto upgrade variable (always FALSE), and introduce
    verify_format and exclusive.

  (svn_wc__db_pdh_create_wcroot): Rename argument.
  (CHECK_MINIMAL_WCROOT): New macro.

* subversion/libsvn_wc/wc_db_wcroot.c
  (svn_wc__db_open): Initialize variables that affect opening db files.
  (svn_wc__db_pdh_create_wcroot): Remove upgrade code. Only verify versions.
  (svn_wc__db_wcroot_parse_local_abspath): Use config from db instead of
    reparsing it from inside a loop. Update caller.

* subversion/tests/cmdline/upgrade_tests.py
  (upgrade_from_1_7): Rename to ...
  (upgrade_from_1_7_conflict): ... this, update comment and remove XFail.
  (test_list): Update reference.

* subversion/tests/libsvn_wc/entries-compat.c
  (create_open): Update comment.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1440008 13f79535-47bb-0310-9956-ffa450edef68