osc build stopped working on my Tumbleweed installation at least a few days ago
(but it's possibly been broken for a while -- I don't do "osc build"
particularly frequently). All builds fail (regardless of the package or
project).

% osc build
... snip ...
[    3s] + exec rpmbuild -ba --define '_srcdefattr (-,root,root)' --nosignature
/home/abuild/rpmbuild/SOURCES/containerd.spec
[    3s] rpmbuild: symbol lookup error: /usr/lib64/librpmbuild.so.9: undefined
symbol: rpmPushMacroFlags

% rpm -q rpm-build librpmbuild9
rpm-build-4.16.0-1.1.x86_64
librpmbuild9-4.16.0-1.1.x86_64

% cat /etc/os-release
NAME="openSUSE Tumbleweed"
# VERSION="20210128"
ID="opensuse-tumbleweed"
ID_LIKE="opensuse suse"
VERSION_ID="20210128"
PRETTY_NAME="openSUSE Tumbleweed"
ANSI_COLOR="0;32"
CPE_NAME="cpe:/o:opensuse:tumbleweed:20210128"
BUG_REPORT_URL="https://bugs.opensuse.org"
HOME_URL="https://www.opensuse.org/"
DOCUMENTATION_URL="https://en.opensuse.org/Portal:Tumbleweed"
LOGO="distributor-logo"