Index: Python/compile.c
===================================================================
--- Python/compile.c.orig	2008-01-24 17:19:55.148321400 +0100
+++ Python/compile.c	2008-01-24 17:28:13.663317600 +0100
@@ -1735,8 +1735,11 @@
 	basicblock *loop, *orelse, *end, *anchor = NULL;
 	int constant = expr_constant(s->v.While.test);
 
-	if (constant == 0)
+	if (constant == 0) {
+		if (s->v.While.orelse)
+			VISIT_SEQ(c, stmt, s->v.While.orelse);
 		return 1;
+	}
 	loop = compiler_new_block(c);
 	end = compiler_new_block(c);
 	if (constant == -1) {
Index: Lib/test/test_grammar.py
===================================================================
--- Lib/test/test_grammar.py.orig	2008-01-24 17:25:29.496728100 +0100
+++ Lib/test/test_grammar.py	2008-01-24 17:31:00.033019200 +0100
@@ -498,6 +498,15 @@
         while 0: pass
         else: pass
 
+        # Issue1920: "while 0" is optimized away,
+        # ensure that the "else" clause is still present.
+        x = 0
+        while 0:
+            x = 1
+        else:
+            x = 2
+        self.assertEquals(x, 2)
+
     def testFor(self):
         # 'for' exprlist 'in' exprlist ':' suite ['else' ':' suite]
         for i in 1, 2, 3: pass