Changing svn_checksum__from_digest()'s signature

[Blair Zajac]

In case of an illegal svn_checksum_kind_t being passed to 
svn_checksum__from_digest(), I want to change it from

svn_checksum_t *
svn_checksum__from_digest(const unsigned char *digest,
                          svn_checksum_kind_t kind,
                          apr_pool_t *result_pool);
to

svn_error_t *
svn_checksum__from_digest(svn_checksum_t **checksum,
                          const unsigned char *digest,
                          svn_checksum_kind_t kind,
                          apr_pool_t *result_pool);

This is to prevent a core dump we've observed with our RPC server.

The function is in a public .h file but shown as private.  Do I need to 
add svn_checksum__from_digest2() or can I just change it?

Blair