update-alternatives --install fails when changing the follower name

[opoplawski]

Current state with follower name as zabbix-proxy-systemd:

# alternatives --display zabbix-proxy
zabbix-proxy - status is auto.
 link currently points to /usr/sbin/zabbix_proxy_mysql
/usr/sbin/zabbix_proxy_mysql - priority 10
 follower zabbix-proxy-systemd: /usr/lib/systemd/system/zabbix-proxy-mysql.service
Current `best' version is /usr/sbin/zabbix_proxy_mysql.
# ls -l /etc/alternatives/zabb*
lrwxrwxrwx. 1 root root 28 Nov  6 12:42 /etc/alternatives/zabbix-proxy -> /usr/sbin/zabbix_proxy_mysql*
lrwxrwxrwx. 1 root root 50 Jan 12 17:33 /etc/alternatives/zabbix-proxy-systemd -> /usr/lib/systemd/system/zabbix-proxy-mysql.service

Try to change that:

# /usr/sbin/update-alternatives --install /usr/sbin/zabbix_proxy     zabbix-proxy /usr/sbin/zabbix_proxy_mysql 10         --slave /usr/lib/systemd/system/zabbix-proxy.service zabbix-proxy.service             /usr/lib/systemd/system/zabbix-proxy-mysql.service --verbose
reading /var/lib/alternatives/zabbix-proxy

Things are broken:

# ls -l /etc/alternatives/zabbix* /usr/lib/systemd/system/zabbix-proxy.service
ls: cannot access '/usr/lib/systemd/system/zabbix-proxy.service': No such file or directory
lrwxrwxrwx. 1 root root 28 Nov  6 12:42 /etc/alternatives/zabbix-proxy -> /usr/sbin/zabbix_proxy_mysql*
# # alternatives --display zabbix-proxy
zabbix-proxy - status is auto.
 link currently points to /usr/sbin/zabbix_proxy_mysql
/usr/sbin/zabbix_proxy_mysql - priority 10
Current `best' version is /usr/sbin/zabbix_proxy_mysql.

If it is run again, then we are working:

# /usr/sbin/update-alternatives --install /usr/sbin/zabbix_proxy     zabbix-proxy /usr/sbin/zabbix_proxy_mysql 10         --slave /usr/lib/systemd/system/zabbix-proxy.service zabbix-proxy.service             /usr/lib/systemd/system/zabbix-proxy-mysql.service --verbose
reading /var/lib/alternatives/zabbix-proxy
# ls -l /etc/alternatives/zabbix* /usr/lib/systemd/system/zabbix-proxy.service
lrwxrwxrwx. 1 root root 28 Nov  6 12:42 /etc/alternatives/zabbix-proxy -> /usr/sbin/zabbix_proxy_mysql*
lrwxrwxrwx. 1 root root 50 Jan 12 17:38 /etc/alternatives/zabbix-proxy.service -> /usr/lib/systemd/system/zabbix-proxy-mysql.service
lrwxrwxrwx. 1 root root 38 Jan 12 17:38 /usr/lib/systemd/system/zabbix-proxy.service -> /etc/alternatives/zabbix-proxy.service