improve checks

lib/vm.sh

@@ -5,10 +5,13 @@
 #           vm_exec, vm_put, vm_reboot, VM_GIT_SSH and VM_GIT_URL.
 
 SMOKETEST_STATE="${XDG_CACHE_HOME:-$HOME/.cache}/coredesktop-dev/smoketest"
+# IMAGES and KVM_DEVICE are used by smoketest.sh
+# shellcheck disable=SC2034
 IMAGES="$SMOKETEST_STATE/images"
 # Shared with every VM as its /var/cache/pacman/pkg, so packages download once
 PKG_CACHE="$SMOKETEST_STATE/pkg"
 SSH_KEY="$SMOKETEST_STATE/id_ed25519"
+# shellcheck disable=SC2034
 KVM_DEVICE="${KVM_DEVICE:-/dev/kvm}"
 
 VM_USER=tester
@@ -43,8 +46,8 @@ ensure_ssh_key() {
 }
 
 free_port() {
-  local port i
-  for i in $(seq 50); do
+  local port
+  for _ in $(seq 50); do
     port=$((20000 + RANDOM % 20000))
     [ -z "$(ss -Hltn "( sport = :$port )" 2> /dev/null)" ] && { echo "$port"; return 0; }
   done