mininet's pingall doesn't work correctly with iputils-ping and locale different to English

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 20.04.3 LTS
Release: 20.04
Codename: focal

mininet version 2.2.2-5ubuntu1, but also tested with 2.3.0-1ubuntu1 from impish.

mininet is not able to parse the ping output in a localised environment, for languages other than English. For example, this is running on fr_FR.UTF-8:

$ sudo mn
*** Creating network
*** Adding controller
*** Adding hosts:
h1 h2
*** Adding switches:
s1
*** Adding links:
(h1, s1) (h2, s1)
*** Configuring hosts
h1 h2
*** Starting controller
c0
*** Starting 1 switches
s1 ...
*** Starting CLI:
mininet> pingall
*** Ping: testing ping reachability
h1 -> *** Error: could not parse ping output: PING 10.0.0.2 (10.0.0.2) 56(84) bytes of data.
64 octets de 10.0.0.2 : icmp_seq=1 ttl=64 temps=4.36 ms

--- statistiques ping 10.0.0.2 ---
1 paquets transmis, 1 reçus, 0 % paquets perdus, temps 0 ms
rtt min/avg/max/mdev = 4.355/4.355/4.355/0.000 ms

X
h2 -> *** Error: could not parse ping output: PING 10.0.0.1 (10.0.0.1) 56(84) bytes of data.
64 octets de 10.0.0.1 : icmp_seq=1 ttl=64 temps=0.978 ms

--- statistiques ping 10.0.0.1 ---
1 paquets transmis, 1 reçus, 0 % paquets perdus, temps 0 ms
rtt min/avg/max/mdev = 0.978/0.978/0.978/0.000 ms

X
*** Results: 100% dropped (0/2 received)

I can workaround the problem with LANG=C:

$ LANG=C sudo mn
*** Creating network
*** Adding controller
*** Adding hosts:
h1 h2
*** Adding switches:
s1
*** Adding links:
(h1, s1) (h2, s1)
*** Configuring hosts
h1 h2
*** Starting controller
c0
*** Starting 1 switches
s1 ...
*** Starting CLI:
mininet> pingall
*** Ping: testing ping reachability
h1 -> h2
h2 -> h1
*** Results: 0% dropped (2/2 received)

Bug filed upstream: https://github.com/mininet/mininet/issues/1063