Check for time.struct_time in addition to tuples. Use 3 characters

for zone hours. Fixes #499169.

Lib/test/test_imaplib.py

@@ -0,0 +1,14 @@
+from test_support import verify,verbose
+import imaplib
+import time
+
+# We can check only that it successfully produces a result,
+# not the correctness of the result itself, since the result
+# depends on the timezone the machine is in.
+
+timevalues = [2000000000, 2000000000.0, time.localtime(2000000000),
+              "18-May-2033 05:33:20 +0200"]
+
+for t in timevalues:
+    imaplib.Time2Internaldate(t)
+