Try the nuclear option

scripts/install_redhat_centos_7.sh

@@ -4,7 +4,49 @@
 mpi_lib=mpich-devel
 
 # CentOS 7 is EOL as of 2024-06-30, so we need to use the vault
-sed -i 's,^mirrorlist=,#,; s,^#baseurl=http://mirror\.centos\.org/centos/$releasever,baseurl=https://vault.centos.org/7.9.2009,' /etc/yum.repos.d/CentOS-Base.repo
+contents=$(cat << EOF
+[base]
+name=CentOS-$releasever - Base
+baseurl=http://vault.centos.org/7.9.2009/os/$basearch/
+gpgcheck=1
+gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
+
+[updates]
+name=CentOS-$releasever - Updates
+baseurl=http://vault.centos.org/7.9.2009/updates/$basearch/
+gpgcheck=1
+gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
+
+[extras]
+name=CentOS-$releasever - Extras
+baseurl=http://vault.centos.org/7.9.2009/extras/$basearch/
+gpgcheck=1
+gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
+
+[centosplus]
+name=CentOS-$releasever - Plus
+baseurl=http://vault.centos.org/7.9.2009/centosplus/$basearch/
+gpgcheck=1
+enabled=0
+gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
+
+[centos-sclo-rh]
+name=CentOS-$releasever - SCLo rh
+baseurl=http://vault.centos.org/7.9.2009/sclo/$basearch/rh/
+gpgcheck=1
+enabled=1
+gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
+
+[centos-sclo-sclo]
+name=CentOS-$releasever - SCLo sclo
+baseurl=http://vault.centos.org/7.9.2009/sclo/$basearch/sclo/
+gpgcheck=1
+enabled=1
+gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
+EOF
+)
+echo "${contents}" > /etc/yum.repos.d/CentOS-Base.repo
+
 yum clean all
 yum makecache