#15109: revert '%'->'format' changes in 4b105d328fe7 to fix regression.

With '%', non-ascii worked because the '%' automatically got promoted to
unicode.  With format that doesn't happen, which led to encoding errors.  This
fix goes back to using %, and adds a test to make sure non-ascii string values
work in iterdump.

Lib/sqlite3/test/dump.py

@@ -29,6 +29,8 @@ class DumpTests(unittest.TestCase):
                 ,
                 "INSERT INTO \"t1\" VALUES(2,'foo2',30,30);"
                 ,
+                u"INSERT INTO \"t1\" VALUES(3,'f\xc3\xb6',40,10);"
+                ,
                 "CREATE TABLE t2(id integer, t2_i1 integer, " \
                 "t2_i2 integer, primary key (id)," \
                 "foreign key(t2_i1) references t1(t1_i1));"