Don't error out with "svn: E200030: sqlite: no such table: nodes"
when opening old working copies and if compiled with SVN_DEBUG.
Instead, print a message advising an upgrade.

I found this problem while trying to use a format 18 WC with a trunk client.

* subversion/libsvn_wc/wc_db_wcroot.c
  (svn_wc__db_wcroot_parse_local_abspath): Verification triggers don't
   install properly with old WC format databases, so ignore sqlite errors
   while installing the triggers. Allows old working copies in 1.7-dev
   format to be upgraded to format 29 (at which point there is yet another
   problem which I'll investigate next).


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1463522 13f79535-47bb-0310-9956-ffa450edef68