Report imex and configure success/failure after freeing ongoing

Otherwise it's possible that library user (e.g. test)
tries to start another ongoing process when previous one is
not freed yet.

src/configure.rs

@@ -75,6 +75,8 @@ impl Context {
             }))
             .await;
 
+        self.free_ongoing().await;
+
         if let Err(err) = res.as_ref() {
             progress!(
                 self,
@@ -93,8 +95,6 @@ impl Context {
             progress!(self, 1000);
         }
 
-        self.free_ongoing().await;
-
         res
     }