For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/openSUSE:infrastructure:wiki/openSUSE_Tumbleweed/openSUSE:infrastructure:wiki.repo
zypper refresh
zypper install mediawiki_1_37-UserMerge
For 16.0 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/openSUSE:infrastructure:wiki/16.0/openSUSE:infrastructure:wiki.repo
zypper refresh
zypper install mediawiki_1_37-UserMerge
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/openSUSE:infrastructure:wiki/15.6/openSUSE:infrastructure:wiki.repo
zypper refresh
zypper install mediawiki_1_37-UserMerge