first try

.gitignore

@@ -1 +1,4 @@
-packer_cache/
+/packer_cache/
+/build/
+/http/*.iso
+.*.swp

setup-babelbox.sh

@@ -1,10 +1,8 @@
 #!/bin/sh
 set -e
 
-if [ ! -f http/debian-7.7.0-i386-DVD-1.iso ]; then
-    cd http
-    wget http://cdimage.debian.org/debian-cd/current/i386/iso-dvd/debian-7.7.0-i386-DVD-1.iso
-    cd ..
-fi
+cd http
+wget -c -N http://cdimage.debian.org/debian-cd/current/i386/iso-dvd/debian-7.7.0-i386-DVD-1.iso
+cd ..
 
 packer build debian-babelbox.json