Do not check the kernelfor the OS when inside of Docker containers.

setup.sh

@@ -55,7 +55,11 @@ fi
 ## Main ##
 
 os="$(cat /etc/os-release)"
-os="$os $(uname -a)"
+if [[ ! -f /.dockerenv ]]; then
+	# If we are not in a Docker container, also check what the kernel says.
+	os="$os $(uname -a)"
+	# Docker containers use the host kernel which gives an incorrect reading.
+fi
 
 echo "Making sure all necessary packages are installed..."
 if [[ `which ansible > /dev/null; echo $?` != 0 ]]; then