Fix handling of LOGOPNG when we've got "doppelgangers"

When we've got multiple copies of the same initramfs hard-linked
together, gzip gets unhappy when we start modifying things
later. Explicitly break the links to fix that.

debian/changelog

@@ -5,6 +5,7 @@ debian-cd (3.1.18) UNRELEASED; urgency=medium
   * Remove mention of desktop choice from yaboot boot messages
     (Closes: #783569)
   * Add YA syslinux package to Recommends.
+  * Fix handlinkg of LOGOPNG when we've got "doppelganer" initramfs files
 
  -- Steve McIntyre <93sam@debian.org>  Mon, 20 Apr 2015 12:36:57 +0100
 

tools/boot/stretch/boot-x86

@@ -405,12 +405,15 @@ if [ "$LOGOPNG" ] ; then
     mkdir -p $INITRDDIR
     (
         cd $INITRDDIR
-        gunzip $GTKINITRDGZ
+	# There may be multiple hardlinks to the initrd.gz, so
+	# explicitly break the links here
+        zcat $GTKINITRDGZ > $GTKINITRD
+	rm -f $GTKINITRDGZ
         mkdir -p $INITRDDIR/usr/share/graphics
         cp $LOGOPNG $INITRDDIR/usr/share/graphics/logo_debian.png
         echo usr/share/graphics/logo_debian.png | \
             cpio -oA -H newc -F $GTKINITRD
-        gzip -9 $GTKINITRD
+	gzip -9 $GTKINITRD
     )
     rm -rf $INITRDDIR
 fi