The (c)make scripts generate a wrong sbindir path.
With
-DCMAKE_INSTALL_PREFIX=/usr
-DINSTALL_SCRIPTDIR=bin

It generates an sbindir in galera_recovery of "./bin", which breaks galera_recovery, because "./bin" is a relative path to the current working directory. If the wd of the calling process is not /, then the script breaks at that point.

Build files are available at https://git.archlinux.org/svntogit/packages.git/tree/trunk?h=packages/mariadb