tests/dict2.py: Add combined test for dict(dict) and dict equality.

tests/basics/dict2.py

@@ -8,3 +8,7 @@ print(d['1'], d['2'], d['3'])
 
 d['2'] = 222
 print(d['1'], d['2'], d['3'])
+
+d2 = dict(d)
+print('2' in d2)
+print(id(d) != id(d2), d == d2)