Fix working copy access via a symlink which points to a working copy nested within an unrelated working copy of an unsupported format.
Fix working copy access via a symlink which points to a working copy nested
within an unrelated working copy of an unsupported format.

This patch fixes special_tests 19 and 20 on the 1.7.x branch when run
within a format 30 working copy (backport nomination will follow).

To reproduce the problem fixed by this commit with just a trunk client:
 - Check out a working copy WC1.
 - Check out one nested working copy WC2 within WC1's root dir.
 - Use sqlite3 to set "pragma user_version = 31" in WC1's .svn/wc.db.
 - Create a symlink S within WC1 which points at WC2.
 - Try to run 'svn status' on the symlink S.

* subversion/libsvn_wc/wc_db_wcroot.c
  (svn_wc__db_wcroot_parse_local_abspath): If we find an unsupported working
   copy after traversing upwards from a symlink, and the symlink points to
   a directory, try to find a working copy at that directory instead.

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