Reworking to fit new FS interface.
Reworking to fit new FS interface.

(svn_fs__txn_root_node): Return an svn_fs_root_t.

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