Reset in Rows's drop impl instead of waiting for the next query

src/convenient.rs

@@ -23,16 +23,14 @@ impl<'conn> Statement<'conn> {
     /// Return `true` if a query in the SQL statement it executes returns one or more rows
     /// and `false` if the SQL returns an empty set.
     pub fn exists(&mut self, params: &[&ToSql]) -> Result<bool> {
-        self.reset_if_needed();
+        let mut rows = try!(self.query(params));
         let exists = {
-            let mut rows = try!(self.query(params));
             match rows.next() {
-                Some(_) => Ok(true),
-                None => Ok(false),
+                Some(_) => true,
+                None => false,
             }
         };
-        self.reset_if_needed();
-        return exists;
+        Ok(exists)
     }
 }