Transform a target reference to its source reference following the refspec's
rules
@param out_ where to store the source reference name
@param spec the refspec
@param name the name of the reference to transform
@return 0, git_error_code.GIT_EBUFS or another error
Transform a target reference to its source reference following the refspec's rules
@param out_ where to store the source reference name @param spec the refspec @param name the name of the reference to transform @return 0, git_error_code.GIT_EBUFS or another error