Details in tests

- Added a test for calling 'debug.traceback' after yields inside
hooks. (Lua 5.3 seems to have a bug there.)

- Removed test "repeat test with '__open' metamethod instead of a
function", as the previous test already uses the '__open' metamethod.
(It changed when functions were removed as possible to-be-closed
variables).
diff --git a/testes/coroutine.lua b/testes/coroutine.lua
index f2c0da8..e04207c 100644
--- a/testes/coroutine.lua
+++ b/testes/coroutine.lua
@@ -426,6 +426,10 @@
   while A==0 or B==0 do    -- A ~= 0 when 'x' finishes (similar for 'B','y')
     if A==0 then turn = "A"; assert(T.resume(x)) end
     if B==0 then turn = "B"; assert(T.resume(y)) end
+
+    -- check that traceback works correctly after yields inside hooks
+    debug.traceback(x)
+    debug.traceback(y)
   end
 
   assert(B // A == 7)    -- fact(7) // fact(6)
diff --git a/testes/locals.lua b/testes/locals.lua
index dccda28..a41b6f0 100644
--- a/testes/locals.lua
+++ b/testes/locals.lua
@@ -517,27 +517,15 @@
   end
   assert(s == 35 and numopen == 0)
 
-  -- repeat test with '__open' metamethod instead of a function
-  local function open (x)
-    numopen = numopen + 1
-    local state = setmetatable({x},
-                        {__close = function () numopen = numopen - 1 end})
-    return
-      function (t)   -- iteraction function
-        t[1] = t[1] - 1
-        if t[1] > 0 then return t[1] end
-      end,
-      state,
-      nil,
-      state    -- to-be-closed
-  end
-
   local s = 0
   for i in open(10) do
-     if (i < 5) then break end
-     s = s + i
+    for j in open(10) do
+       if i + j < 5 then goto endloop end
+       s = s + i
+    end
   end
-  assert(s == 35 and numopen == 0)
+  ::endloop::
+  assert(s == 375 and numopen == 0)
 end
 
 print('OK')