swaync-fbcli: fix CPU pegging

hosts/common/programs/swaynotificationcenter/swaync-fbcli

@@ -28,21 +28,22 @@ start() {
 
   trap cleanup SIGINT SIGQUIT SIGTERM
 
-  local extraFbcliArgs=()
+  local timeout=
   case "$event" in
     phone-incoming-call)
-      extraFbcliArgs=("-t" "20")
+      timeout=20
       ;;
     *)
       ;;
   esac
 
+  local cli="fbcli --event $event ${timeout:+ -t $timeout}"
+
   # feedbackd stops playback when the caller exits
   # and fbcli will exit immediately if it has no stdin.
   # so spoof a stdin.
-  # TODO: this maybe pegs CPU at 100% when receiving a call, and never exits?
-  log "fbcli --event $event ${extraFbcliArgs[*]}"
-  /bin/sh -c "true | fbcli --event $event ${extraFbcliArgs[*]}" &
+  log "$cli"
+  /bin/sh -c "sleep $((3 ${timeout:+ + $timeout})) | $cli" &
   child=$!
   wait
 }