Merge branch 'master' into fix-xpcall-error-in-error-handler

Author: mzki

_glua-tests/issues.lua

@@ -468,4 +468,15 @@ function test()
   end)
   assert(not ok)
 end
-test()
+test()
+
+-- issue #459
+function test()
+  local a, b = io.popen("ls", nil)
+  assert(a)
+  assert(b == nil)
+  local a, b = io.popen("ls", nil, nil)
+  assert(a)
+  assert(b == nil)
+end
+test()

iolib.go

@@ -658,6 +658,9 @@ func ioPopen(L *LState) int {
 	cmd := L.CheckString(1)
 	if L.GetTop() == 1 {
 		L.Push(LString("r"))
+	} else if L.GetTop() > 1 && (L.Get(2)).Type() == LTNil {
+		L.SetTop(1)
+		L.Push(LString("r"))
 	}
 	var file *LUserData
 	var err error