Get the Reference Database Backend for this repository.
If a custom refsdb has not been set, the default database for
the repository will be returned (the one that manipulates loose
and packed references in the .git directory).
The refdb must be freed once it's no longer being used by
the user.
@param out_ Pointer to store the loaded refdb
@param repo A repository object
@return 0, or an error code
Get the Reference Database Backend for this repository.
If a custom refsdb has not been set, the default database for the repository will be returned (the one that manipulates loose and packed references in the .git directory).
The refdb must be freed once it's no longer being used by the user.
@param out_ Pointer to store the loaded refdb @param repo A repository object @return 0, or an error code