debian/roll-tarball.sh: Support tarring up the HEAD of the current branch.

debian/roll-tarballs.sh

@@ -52,13 +52,13 @@ else
 fi
 
 if [ x"$RELEASE" == "xHEAD" ]; then
-    CHECKOUT="HEAD"
+    CHECKOUT=refs/heads/$(git rev-parse --abbrev-ref HEAD)
 fi
 
 if ! git rev-parse --verify -q "$CHECKOUT" >/dev/null; then
     echo "   '${RELEASE}' is not a valid release number because there is no git tag named ${CHECKOUT}."
     echo "   Please specify one of the following releases:"
-    echo "HEAD"
+    echo "HEAD (on branch `git rev-parse --abbrev-ref HEAD`)"
     git tag -l | grep "^redist" | cut -f2 -d"/" | sort -u
     exit 1
 fi