gnunet-core --connection-status output nothing

I have installed gnunet 0.28 following
https://docs.gnunet.org/latest/installing.html

from git.

```
sudo -u gnunet gnunet-arm -I
Services (excluding stopped services):
(started: 20 / stopped: 14)
cadet (binary=3D'gnunet-service-cadet', status=3Dstarted)
core (binary=3D'gnunet-service-core', status=3Dstarted)
datastore (binary=3D'gnunet-service-datastore', status=3Dstarted)
dht (binary=3D'gnunet-service-dht', status=3Dstarted)
gns (binary=3D'gnunet-service-gns', status=3Dstarted)
hostlist (binary=3D'gnunet-daemon-hostlist', status=3Dstarted)
namecache (binary=3D'gnunet-service-namecache', status=3Dstarted)
nat (binary=3D'gnunet-service-nat', status=3Dstarted)
nse (binary=3D'gnunet-service-nse', status=3Dstarted)
peerstore (binary=3D'gnunet-service-peerstore', status=3Dstarted)
pils (binary=3D'gnunet-service-pils', status=3Dstarted)
rest (binary=3D'gnunet-rest-server', status=3Dstarted)
revocation (binary=3D'gnunet-service-revocation', status=3Dstarted)
rps (binary=3D'gnunet-service-rps', status=3Dstarted)
setu (binary=3D'gnunet-service-setu', status=3Dstarted)
statistics (binary=3D'gnunet-service-statistics', status=3Dstarted)
topology (binary=3D'gnunet-daemon-topology', status=3Dstarted)
transport (binary=3D'gnunet-service-transport', status=3Dstarted)
communicator-tcp (binary=3D'gnunet-communicator-tcp', status=3Dstarted)
communicator-udp (binary=3D'gnunet-communicator-udp', status=3Dstarted)
```

```
gnunet-arm -I
Services (excluding stopped services):
(started: 3 / stopped: 6)
fs (binary=3D'gnunet-service-fs', status=3Dstarted)
namestore (binary=3D'gnunet-service-namestore', status=3Dstarted)
zonemaster (binary=3D'gnunet-service-zonemaster', status=3Dstarted)
```

But 'gnunet-core --connection-status' just returns silently. I should
have at least 1 connection, right? How to debug this problem?