Galera-4 package breaks yum update from 10.3 to 10.4

In 10.4 the Galera RPM package name has changed from "galera" to "galera-4". This only makes sense if it is supposed to be installed alongside Galera 3, which is partially hinted by the use of a separate subdirectory in /usr/lib64. However, such con-existence is impossible due to overlapping files:

/usr/bin/garb-systemd
/usr/bin/garbd

In the RHEL world, the common and preferred way to update packages (even between significant releases) is via "yum update". While our upgrade guide does say that one need to uninstall 10.3 and then install 10.4, this is more error-prone than simply doing an upgrade, which is, except for this Galera packaging issue, is completely possible.

The issue may be fixed in several ways:

• If Galera 3 and Galera 4 were indeed meant to co-exist, then rename the two conflicting files in Galera 4. It also a good idea to rename the Galera 4 library as it uses the same library name as Galera 3, and while adding an LD_LIBRARY_PATH to 104. systemd unit file may help, a con-existing 10.3 might still wrongly pick up the Galera 4 library based on how ldd configures its cache.

• If they were not meant to co-exist, then reusing the name "galera" for the package would had been the best choice; now is a bit too late for this, so add an "Obsoletes: galera" to the RPM spec file instead - as a result, installing the Galera 4 RPM will first remove the Galera 3 RPM.