updated for version 7.3.516

Problem:    extend(o, o) may crash Vim.
Solution:   Fix crash and add test. (Thinca and Hirohito Higashi)

src/testdir/test55.in

@@ -352,6 +352,24 @@ let l = [0, 1, 2, 3]
 :let dict4copy = deepcopy(dict4)
 :$put =(l == lcopy)
 :$put =(dict4 == dict4copy)
+:"
+:" Pass the same List to extend()
+:let l = [1, 2, 3, 4, 5]
+:call extend(l, l)
+:$put =string(l)
+:"
+:" Pass the same Dict to extend()
+:let d = { 'a': {'b': 'B'}}
+:call extend(d, d)
+:$put =string(d)
+:"
+:" Pass the same Dict to extend() with "error"
+:try
+:  call extend(d, d, "error")
+:catch
+:  $put =v:exception[:15] . v:exception[-1:-1]
+:endtry
+:$put =string(d)
 :endfun
 :"
 :call Test(1, 2, [3, 4], {5: 6})  " This may take a while

src/testdir/test55.ok

@@ -111,3 +111,7 @@ caught a:000[3]
 0
 1
 1
+[1, 2, 3, 4, 5, 1, 2, 3, 4, 5]
+{'a': {'b': 'B'}}
+Vim(call):E737: a
+{'a': {'b': 'B'}}