install usrmerge if proper symlink does not exist

install

@@ -13,7 +13,7 @@
 # https://github.com/armbian/config/blob/master/debian-software
 # https://forum.openmediavault.org/index.php/Thread/25062-Install-OMV5-on-Debian-10-Buster/
 #
-# version: 1.6.13
+# version: 1.6.14
 #
 
 if [[ $(id -u) -ne 0 ]]; then
@@ -185,6 +185,11 @@ if [[ ! ${hostname} =~ ${regex} ]]; then
     exit 6
 fi
 
+# install usrmerge package if /usr symlink don't exist
+if [ "$(readlink -f /lib)" != "/usr/lib" ]; then
+  apt-get --yes install usrmerge
+fi
+
 # Add Debian signing keys to raspbian to prevent apt-get update failures
 # when OMV adds security and/or backports repos
 if grep -rq raspberrypi.org /etc/apt/*; then