Index: grub-2.02~beta2/util/grub.d/10_linux.in
===================================================================
--- grub-2.02~beta2.orig/util/grub.d/10_linux.in
+++ grub-2.02~beta2/util/grub.d/10_linux.in
@@ -45,12 +45,14 @@ esac
 
 # btrfs may reside on multiple devices. We cannot pass them as value of root= parameter
 # and mounting btrfs requires user space scanning, so force UUID in this case.
-if [ "x${GRUB_DEVICE_UUID}" = "x" ] || [ "x${GRUB_DISABLE_LINUX_UUID}" = "xtrue" ] \
+if ( [ "x${GRUB_DEVICE_UUID}" = "x" ] || [ "x${GRUB_DISABLE_LINUX_UUID}" = "xtrue" ] \
     || ! test -e "/dev/disk/by-uuid/${GRUB_DEVICE_UUID}" \
-    || ( test -e "${GRUB_DEVICE}" && uses_abstraction "${GRUB_DEVICE}" lvm ); then
+    ||  uses_abstraction "${GRUB_DEVICE}" lvm  ) && test -e "${GRUB_DEVICE}"; then
   LINUX_ROOT_DEVICE=${GRUB_DEVICE}
 else
-  LINUX_ROOT_DEVICE=UUID=${GRUB_DEVICE_UUID}
+  if [ "x${GRUB_DEVICE_UUID}" != "x" ]; then
+    LINUX_ROOT_DEVICE=UUID=${GRUB_DEVICE_UUID}
+  fi
 fi
 
 if [ "x$GRUB_CONMODE" != "x" ]; then
Index: grub-2.02~beta2/util/grub.d/20_linux_xen.in
===================================================================
--- grub-2.02~beta2.orig/util/grub.d/20_linux_xen.in
+++ grub-2.02~beta2/util/grub.d/20_linux_xen.in
@@ -55,12 +55,14 @@ esac
 
 # btrfs may reside on multiple devices. We cannot pass them as value of root= parameter
 # and mounting btrfs requires user space scanning, so force UUID in this case.
-if [ "x${GRUB_DEVICE_UUID}" = "x" ] || [ "x${GRUB_DISABLE_LINUX_UUID}" = "xtrue" ] \
+if ( [ "x${GRUB_DEVICE_UUID}" = "x" ] || [ "x${GRUB_DISABLE_LINUX_UUID}" = "xtrue" ] \
     || ! test -e "/dev/disk/by-uuid/${GRUB_DEVICE_UUID}" \
-    || ( test -e "${GRUB_DEVICE}" && uses_abstraction "${GRUB_DEVICE}" lvm ); then
+    || uses_abstraction "${GRUB_DEVICE}" lvm ) && test -e "${GRUB_DEVICE}"; then
   LINUX_ROOT_DEVICE=${GRUB_DEVICE}
 else
-  LINUX_ROOT_DEVICE=UUID=${GRUB_DEVICE_UUID}
+  if [ "x${GRUB_DEVICE_UUID}" != "x" ]; then
+    LINUX_ROOT_DEVICE=UUID=${GRUB_DEVICE_UUID}
+  fi
 fi
 
 # Allow overriding GRUB_CMDLINE_LINUX and GRUB_CMDLINE_LINUX_DEFAULT.