Save the full sha1sum of the commit we generate patch-4.y-*-gitN from

We save off the top commit into a new file called 'gitrev'.  This will help
us automate exploded tree creation by providing a simple file to read to
get the exact upstream commit to use as the base.

gitrev

@@ -0,0 +1 @@
+bcee19f424a0d8c26ecf2607b73c690802658b29

scripts/generate-git-snapshot.sh

@@ -19,9 +19,11 @@ pushd $LINUX_GIT
 git diff v$VER.. > /tmp/patch-$VER-git$NEWGIT
 xz -9 /tmp/patch-$VER-git$NEWGIT
 DESC=$(git describe)
+git rev-list --max-count=1 HEAD > /tmp/gitrev
 popd
 
 mv /tmp/patch-$VER-git$NEWGIT.xz .
+mv /tmp/gitrev .
 
 perl -p -i -e 's|%global baserelease.*|%global baserelease 0|' kernel.spec