Don't assume that the presence of /etc/default/grub or

/etc/default/grub.d/*.cfg means that any particular item is set in it
(LP: #1199731).

debian/changelog

@@ -9,6 +9,9 @@ grub2 (2.00-15) UNRELEASED; urgency=low
   * Make the description of grub-firmware-qemu a little more generic, rather
     than assuming that bochsbios provides qemu's default BIOS image (closes:
     #714277).
+  * Don't assume that the presence of /etc/default/grub or
+    /etc/default/grub.d/*.cfg means that any particular item is set in it
+    (LP: #1199731).
 
   [ Debconf translations ]
   * Hungarian (Dr. Nagy Elemér Károly).

debian/config.in

@@ -38,13 +38,14 @@ esac
 
 for x in /etc/default/grub /etc/default/grub.d/*.cfg ; do
   if [ -e "$x" ]; then
-    DEFAULT_FOUND="yes"
     . "$x"
   fi
 done
 
-if [ "$DEFAULT_FOUND" = "yes" ]; then
+if [ "${GRUB_CMDLINE_LINUX+set}" = set ]; then
   db_set grub2/linux_cmdline "$GRUB_CMDLINE_LINUX"
+fi
+if [ "${GRUB_CMDLINE_LINUX_DEFAULT+set}" = set ]; then
   db_set grub2/linux_cmdline_default "$GRUB_CMDLINE_LINUX_DEFAULT"
 fi
 

debian/postinst.in

@@ -284,11 +284,10 @@ config_item()
 {
   for x in /etc/default/grub /etc/default/grub.d/*.cfg; do
     if [ -e "$x" ]; then
-      DEFAULT_FOUND="yes"
       . "$x"
     fi
   done
-  if [ "$DEFAULT_FOUND" = "yes" ]; then
+  if [ "$(eval echo "\${$1+set}")" = set ]; then
     eval echo "\$$1"
   else
     return