grub2: fix lost pre-prepared files detail

partly lost in some adjustments that were made to the submitted work,
which was focused on restoring the 'start installer' entry.

there is no need for dynamic setting of these two `source` imports in the
default file, in fact user modifications should also use the fixed import
commands in future.

note that the old placeholders however remain replaced, which inject
precisely this string, for backwards compatibility.

Gbp-Dch: Ignore

scripts/build/binary_loopback_cfg

@@ -203,8 +203,6 @@ fi
 # Assembling debian-installer configuration
 if [ "${LB_DEBIAN_INSTALLER}" != "none" ]; then
 	ENABLE_INSTALL_MENU="true"
-	LINUX_INSTALL="source /boot/grub/install_start.cfg"
-	LINUX_ADVANCED_INSTALL="source /boot/grub/install.cfg"
 
 	KERNEL_DI="/install/vmlinuz"
 	INITRD_DI="/install/initrd.gz"
@@ -250,8 +248,6 @@ escape_for_sed() {
 # Those without '@' markers are for backwards compatibility
 sed -i \
     -e "s|@LINUX_LIVE@|$(escape_for_sed "${LINUX_LIVE}")|" \
-    -e "s|@LINUX_INSTALL@|${LINUX_INSTALL}|" \
-    -e "s|@LINUX_ADVANCED_INSTALL@|${LINUX_ADVANCED_INSTALL}|" \
     -e "s|@KERNEL_GI@|${KERNEL_GI}|" \
     -e "s|@INITRD_GI@|${INITRD_GI}|" \
     -e "s|@APPEND_GI@|${APPEND_GI}|" \
@@ -270,8 +266,8 @@ sed -i \
     -e "s|@MEMTEST_BIN@|${MEMTEST_BIN}|" \
     -e "s|@MEMTEST_VERSION@|${LB_MEMTEST}|" \
     -e "s|LINUX_LIVE|$(escape_for_sed "${LINUX_LIVE}")|" \
-    -e "s|LINUX_INSTALL|${LINUX_INSTALL}|" \
-    -e "s|LINUX_ADVANCED_INSTALL|${LINUX_ADVANCED_INSTALL}|" \
+    -e "s|LINUX_INSTALL|source /boot/grub/install_start.cfg|" \
+    -e "s|LINUX_ADVANCED_INSTALL|source /boot/grub/install.cfg|" \
     -e "s|MEMTEST|${MEMTEST}|" \
     -e "s|KERNEL_GI|${KERNEL_GI}|" \
     -e "s|INITRD_GI|${INITRD_GI}|" \

share/bootloaders/grub-pc/grub.cfg

@@ -47,12 +47,11 @@ play 960 440 1 0 4 440 1
 # Installer (if any)
 if @ENABLE_INSTALL_MENU@; then
 
-@LINUX_INSTALL@
+source	/boot/grub/install_start.cfg
 
 submenu 'Advanced install options...' --hotkey=a {
 
-# More installer entries (if any)
-@LINUX_ADVANCED_INSTALL@
+	source	/boot/grub/install.cfg
 
 }
 fi