fails:OpenSSL::X509::Certificate#serial= returns the argument
fails:OpenSSL::X509::Certificate#serial= raises TypeError if argument is nil
fails:OpenSSL::X509::Certificate#serial= raises TypeError if argument is not a OpenSSL::BN
fails:"OpenSSL::X509::Certificate#serial= returns the argument"
fails:"OpenSSL::X509::Certificate#serial= raises TypeError if argument is nil"
fails:"OpenSSL::X509::Certificate#serial= raises TypeError if argument is not a OpenSSL::BN"
