Fix valgrind problem with invalid memory read
diff --git a/Modules/_sqlite/statement.c b/Modules/_sqlite/statement.c
index a8a9cf5..0c93651 100644
--- a/Modules/_sqlite/statement.c
+++ b/Modules/_sqlite/statement.c
@@ -48,8 +48,6 @@
     char* sql_cstr;
 
     self->st = NULL;
-
-    self->st = NULL;
     self->in_use = 0;
 
     if (PyString_Check(sql)) {
@@ -80,6 +78,7 @@
 
     if (rc == SQLITE_OK && check_remaining_sql(tail)) {
         (void)sqlite3_finalize(self->st);
+        self->st = NULL;
         rc = PYSQLITE_TOO_MUCH_SQL;
     }