[ale] Can't ping localhost

[DJ-Pfulio]

$ ping localhost
PING localhost (127.0.0.1) 56(84) bytes of data.
^C
--- localhost ping statistics ---
6 packets transmitted, 0 received, 100% packet loss, time 5040ms

Huh? 6 dropped packets.

$ ifconfig lo
lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:41 errors:0 dropped:0 overruns:0 frame:0
          TX packets:41 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1
          RX bytes:3444 (3.4 KB)  TX bytes:3444 (3.4 KB)

and

$ head -n 5 /etc/hosts
# Ansible managed: /home/jp/.ansible/jdpfu.com/templates/etc_hosts.j2
modified on 2017-03-19 21:50:56 by jp on lubuntu

127.0.0.1 localhost

I'm at a loss to explain it.  Google hasn't found a solution.  Tried a
sysctl.conf setting - no joy.

Not really an emergency, but bothersome. Only see this on 1 machine.