「dnf coprを有効にする@spacewalkproject/spacewalk-2.10-client」追加エラー

Fedora 31サーバーの1つにspacewalkクライアントをインストールしようとすると、このエラーが発生します。

# dnf copr enable @spacewalkproject/spacewalk-2.10-client
Enabling a Copr repository. Please note that this repository is not part of the main distribution, and quality may vary.

The Fedora Project does not exercise any power over the contents of this repository beyond the rules outlined in the Copr FAQ at <https://docs.pagure.org/copr.copr/user_documentation.html#what-i-can-build-in-copr>, and packages are not held to any quality or security level. 
Please do not file bug reports about these packages in Fedora Bugzilla. In case of problems, contact the owner of this repository.

Do you really want to enable copr.fedorainfracloud.org/@spacewalkproject/spacewalk-2.10-client? [y/N]: y
Error: This repository does not have any builds yet so you cannot enable it now.

サーバーAにインストールできたと思いますが、サーバーBで同じ操作を試みると、このエラーが発生します。違いが何なのかよくわかりません。

Server A $ cat /etc/os-release .
NAME=Fedora
VERSION="31 (Server Edition)"
ID=fedora
VERSION_ID=31
VERSION_CODENAME=""
PLATFORM_ID="platform:f31"
PRETTY_NAME="Fedora 31 (Server Edition)"
ANSI_COLOR="0;34"
LOGO=fedora-logo-icon
CPE_NAME="cpe:/o:fedoraproject:fedora:31"
HOME_URL="https://fedoraproject.org/"
DOCUMENTATION_URL="https://docs.fedoraproject.org/en-US/fedora/f31/system-administrators-guide/"
SUPPORT_URL="https://fedoraproject.org/wiki/Communicating_and_getting_help"
BUG_REPORT_URL="https://bugzilla.redhat.com/"
REDHAT_BUGZILLA_PRODUCT="Fedora"
REDHAT_BUGZILLA_PRODUCT_VERSION=31
REDHAT_SUPPORT_PRODUCT="Fedora"
REDHAT_SUPPORT_PRODUCT_VERSION=31
PRIVACY_POLICY_URL="https://fedoraproject.org/wiki/Legal:PrivacyPolicy"
VARIANT="Server Edition"
VARIANT_ID=server

Server B# cat /etc/os-release
NAME=Fedora
VERSION="31 (Server Edition)"
ID=fedora
VERSION_ID=31
VERSION_CODENAME=""
PLATFORM_ID="platform:f31"
PRETTY_NAME="Fedora 31 (Server Edition)"
ANSI_COLOR="0;34"
LOGO=fedora-logo-icon
CPE_NAME="cpe:/o:fedoraproject:fedora:31"
HOME_URL="https://fedoraproject.org/"
DOCUMENTATION_URL="https://docs.fedoraproject.org/en-US/fedora/f31/system-administrators-guide/"
SUPPORT_URL="https://fedoraproject.org/wiki/Communicating_and_getting_help"
BUG_REPORT_URL="https://bugzilla.redhat.com/"
REDHAT_BUGZILLA_PRODUCT="Fedora"
REDHAT_BUGZILLA_PRODUCT_VERSION=31
REDHAT_SUPPORT_PRODUCT="Fedora"
REDHAT_SUPPORT_PRODUCT_VERSION=31
PRIVACY_POLICY_URL="https://fedoraproject.org/wiki/Legal:PrivacyPolicy"
VARIANT="Server Edition"
VARIANT_ID=server

これは私が以前にインストールできるシステムの1つです。

# rhn_register --version
 rhn_register (Spacewalk Client Tools) 2.10.10-1.fc31
 Copyright (C) 1999--2014 Red Hat, Inc.
 Licensed under the terms of the GPLv2.

# cat /etc/redhat-release
 Fedora release 31 (Thirty One)