cloud lxc template leaves half-written files if interrupted

Happened two times already for me, once on a network glitch (where the wget failed) and once where it never finished so I had to kill wget.

Eg:

drwx------ 2 root root 4096 Oct 8 10:28 tmp.jFQHxoBsm0
-rw-r--r-- 1 root root 179044352 Oct 8 01:02 ubuntu-12.04-server-cloudimg-amd64-root.tar.gz
-rw-r--r-- 1 root root 1556480 Oct 8 10:28 ubuntu-12.04-server-cloudimg-amd64.tar.gz

Doesn't seem like the script can recover from that situation, it just tries to extract the incomplete tarball and fails.

ProblemType: Bug
DistroRelease: Ubuntu 12.10
Package: lxc 0.8.0~rc1-4ubuntu37
ProcVersionSignature: Ubuntu 3.5.0-17.26-generic 3.5.5
Uname: Linux 3.5.0-17-generic x86_64
ApportVersion: 2.6.1-0ubuntu1
Architecture: amd64
Date: Mon Oct 8 10:28:52 2012
InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Alpha amd64 (20120901)
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: lxc
UpgradeStatus: No upgrade log present (probably fresh install)
lxcsyslog:
 Oct 8 14:28:15 sidnei-laptop kernel: [36639.644912] type=1400 audit(1349702895.900:334): apparmor="STATUS" operation="profile_replace" name="lxc-container-default" pid=15205 comm="apparmor_parser"
 Oct 8 14:28:15 sidnei-laptop kernel: [36639.645230] type=1400 audit(1349702895.900:335): apparmor="STATUS" operation="profile_replace" name="lxc-container-default-with-nesting" pid=15205 comm="apparmor_parser"
 Oct 8 14:28:15 sidnei-laptop kernel: [36639.699162] type=1400 audit(1349702895.952:336): apparmor="STATUS" operation="profile_replace" name="/usr/bin/lxc-start" pid=15209 comm="apparmor_parser"
modified.conffile..etc.dnsmasq.d.lxc: [modified]
modified.conffile..etc.lxc.lxc.conf: [modified]
mtime.conffile..etc.dnsmasq.d.lxc: 2012-09-04T09:08:59.313752
mtime.conffile..etc.lxc.lxc.conf: 2012-09-04T09:08:47.312726