Set muc tombstones off

Since only local users can create rooms the threat which this is intended to mitigate doesn't apply

src/freedombone-app-xmpp

@@ -731,10 +731,20 @@ function upgrade_xmpp {
     fi
 
     if grep -q 'muc_room_default_members_only = true' /etc/prosody/prosody.cfg.lua; then
-        sed -i 's|muc_room_default_members_only.*|muc_room_default_members_only = false;' /etc/prosody/prosody.cfg.lua
+        sed -i 's|muc_room_default_members_only.*|muc_room_default_members_only = false;|g' /etc/prosody/prosody.cfg.lua
         xmpp_restart=1
     fi
 
+    if ! grep -q 'muc_tombstones' /etc/prosody/prosody.cfg.lua; then
+        sed -i '/muc_room_lock_timeout/a muc_tombstones = false;' /etc/prosody/prosody.cfg.lua
+        xmpp_restart=1
+    else
+        if ! grep -q 'muc_tombstones = false' /etc/prosody/prosody.cfg.lua; then
+            sed -i 's|muc_tombstones .*|muc_tombstones = false;|g' /etc/prosody/prosody.cfg.lua
+            xmpp_restart=1
+       fi
+    fi
+
     # extra battery saving
     prosody_add_module "csi_compat"
     prosody_add_module "csi_battery_saver"
@@ -1334,6 +1344,7 @@ function xmpp_create_config {
       echo 'muc_room_default_language = "en";';
       echo 'muc_room_locking = false;';
       echo 'muc_room_lock_timeout = 300;';
+      echo 'muc_tombstones = false;';
       echo 'restrict_room_creation = "local";'; } >> /etc/prosody/prosody.cfg.lua
 }