lxc-test-no-new-privs failed with Temporary failure resolving 'archive.ubuntu.com'

It seems this failure only exist in KVM instances.

  FAIL: lxc-tests: lxc-test-no-new-privs (37s)
  ---
  + DONE=0
  + trap cleanup EXIT SIGHUP SIGINT SIGTERM
  + mkdir -p /etc/lxc/
  + cat
  + ARCH=i386
  + type dpkg
  ++ dpkg --print-architecture
  + ARCH=amd64
  + lxc-create -t download -n c1 -- -d ubuntu -r xenial -a amd64
  Setting up the GPG keyring
  Downloading the image index
  Downloading the rootfs
  Downloading the metadata
  The image cache is now ready
  Unpacking the rootfs

  ---
  You just created an Ubuntu xenial amd64 (20190320_07:42) container.

  To enable SSH, run: apt install openssh-server
  No default root or user password are set by LXC.
  + echo 'lxc.no_new_privs = 1'
  + lxc-start -n c1
  ++ lxc-info -n c1 -p -H
  + p1=8818
  + '[' 8818 '!=' -1 ']'
  + sleep 5s
  + lxc-attach -n c1 --clear-env -- apt update -y

  WARNING: apt does not have a stable CLI interface. Use with caution in scripts.

  Err:1 http://archive.ubuntu.com/ubuntu xenial InRelease
    Temporary failure resolving 'archive.ubuntu.com'
  Err:2 http://security.ubuntu.com/ubuntu xenial-security InRelease
    Temporary failure resolving 'security.ubuntu.com'
  Err:3 http://archive.ubuntu.com/ubuntu xenial-updates InRelease
    Temporary failure resolving 'archive.ubuntu.com'
  Reading package lists...
  Building dependency tree...
  Reading state information...
  All packages are up to date.
  W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/xenial/InRelease Temporary failure resolving 'archive.ubuntu.com'
  W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/xenial-updates/InRelease Temporary failure resolving 'archive.ubuntu.com'
  W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/xenial-security/InRelease Temporary failure resolving 'security.ubuntu.com'
  W: Some index files failed to download. They have been ignored, or old ones used instead.
  + lxc-attach -n c1 --clear-env -- apt install -y gcc make

  WARNING: apt does not have a stable CLI interface. Use with caution in scripts.

  Reading package lists...
  Building dependency tree...
  Reading state information...
  The following additional packages will be installed:
    binutils cpp cpp-5 gcc-5 libasan2 libatomic1 libc-dev-bin libc6-dev libcc1-0
    libcilkrts5 libgcc-5-dev libgomp1 libisl15 libitm1 liblsan0 libmpc3 libmpfr4
    libmpx0 libquadmath0 libtsan0 libubsan0 linux-libc-dev manpages manpages-dev
  Suggested packages:
    binutils-doc cpp-doc gcc-5-locales gcc-multilib autoconf automake libtool
    flex bison gdb gcc-doc gcc-5-multilib gcc-5-doc libgcc1-dbg libgomp1-dbg
    libitm1-dbg libatomic1-dbg libasan2-dbg liblsan0-dbg libtsan0-dbg
    libubsan0-dbg libcilkrts5-dbg libmpx0-dbg libquadmath0-dbg glibc-doc
    make-doc man-browser
  The following NEW packages will be installed:
    binutils cpp cpp-5 gcc gcc-5 libasan2 libatomic1 libc-dev-bin libc6-dev
    libcc1-0 libcilkrts5 libgcc-5-dev libgomp1 libisl15 libitm1 liblsan0 libmpc3
    libmpfr4 libmpx0 libquadmath0 libtsan0 libubsan0 linux-libc-dev make
    manpages manpages-dev
  0 upgraded, 26 newly installed, 0 to remove and 0 not upgraded.
  Need to get 28.7 MB of archives.
  After this operation, 102 MB of additional disk space will be used.
  Err:1 http://archive.ubuntu.com/ubuntu xenial/main amd64 libmpfr4 amd64 3.1.4-1
    Temporary failure resolving 'archive.ubuntu.com'
  Err:2 http://archive.ubuntu.com/ubuntu xenial/main amd64 libmpc3 amd64 1.0.3-1
    Temporary failure resolving 'archive.ubuntu.com'
  Err:3 http://archive.ubuntu.com/ubuntu xenial/main amd64 manpages all 4.04-2
    Temporary failure resolving 'archive.ubuntu.com'
  Err:4 http://security.ubuntu.com/ubuntu xenial-security/main amd64 binutils amd64 2.26.1-1ubuntu1~16.04.8
    Temporary failure resolving 'archive.ubuntu.com'
  Err:5 http://archive.ubuntu.com/ubuntu xenial/main amd64 libisl15 amd64 0.16.1-1
    Temporary failure resolving 'archive.ubuntu.com'

It's a bit weird that if I run the command manually, it looks OK
lxc-create -t download -n c1 -- -d ubuntu -r xenial -a amd64
lxc-start -n c1
lxc-attach -n c1 --clear-env -- apt update -y
Hit:1 http://archive.ubuntu.com/ubuntu xenial InRelease
Get:2 http://archive.ubuntu.com/ubuntu xenial-updates InRelease [109 kB]
Get:3 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 Packages [925 kB]
Get:4 http://archive.ubuntu.com/ubuntu xenial-updates/universe amd64 Packages [739 kB]
Get:5 http://security.ubuntu.com/ubuntu xenial-security InRelease [109 kB]
Get:6 http://security.ubuntu.com/ubuntu xenial-security/main amd64 Packages [626 kB]