Add failing test for nix-rust/nix#1541

ci/test.sh

@@ -18,8 +18,25 @@ set -ex
 
 debian/rules vendor
 dpkg-buildpackage --no-sign
+sudo mkdir -p /run/systemd/system/nsncd.d
+sudo tee /run/systemd/system/nsncd.d/crash.conf >/dev/null << EOF
+[service]
+Restart=never
+EOF
 gcc -fPIC -shared -o ci/libnss_whatami.so.2 ci/libnss_whatami.c
 sudo cp ci/libnss_whatami.so.2 /lib
 sudo sed -i 's/passwd:/& whatami/' /etc/nsswitch.conf
 sudo dpkg -i ../nsncd*.deb
+nsncd_pid="$(systemctl show --property=MainPID --value nsncd)"
+
 getent passwd whatami | grep nsncd
+
+for i in `seq 1 20`; do
+    echo "nsncd-ci:x:$((100000 + i)):$USER" | sudo tee /etc/group >/dev/null
+done
+getent initgroups "$USER" | grep 100020
+sudo sed -i '/^nsncd-ci:/d' /etc/group
+
+systemctl status nsncd
+# make sure it didn't die
+kill -0 "$nsncd_pid"