Fixed garbage collection of 'captured' values (pkulchenko/ZeroBraneSt…

…udio#919).

src/mobdebug.lua

@@ -19,7 +19,7 @@ end)("os")
 
 local mobdebug = {
   _NAME = "mobdebug",
-  _VERSION = "0.704",
+  _VERSION = "0.705",
   _COPYRIGHT = "Paul Kulchenko",
   _DESCRIPTION = "Mobile Remote Debugger for the Lua programming language",
   port = os and os.getenv and tonumber((os.getenv("MOBDEBUG_PORT"))) or 8172,
@@ -454,7 +454,7 @@ local function capture_vars(level, thread)
   -- including access to globals, but this causes vars[name] to fail in
   -- restore_vars on local variables or upvalues with `nil` values when
   -- 'strict' is in effect. To avoid this `rawget` is used in restore_vars.
-  setmetatable(vars, { __index = getfenv(func), __newindex = getfenv(func) })
+  setmetatable(vars, { __index = getfenv(func), __newindex = getfenv(func), __mode = "v" })
   return vars
 end