fix(imex): transfer::get_backup must always free ongoing process (#4249)

* fix(imex): transfer::get_backup must always free ongoing process

When the ongoing process is cancelled it is still the responsibility
of whoever took out the ongoing process to free it.  This code was
only freeing the ongoing process when completed normally but not when
cancelled.

* add changelog

Author: flub

CHANGELOG.md

@@ -1,5 +1,12 @@
 # Changelog
 
+## [1.112.3] - Unreleased
+
+### Changes
+
+### Fixes
+- transfer::get_backup now frees ongoing process when cancelled. #4249
+
 ## [1.112.2] - 2023-03-30
 
 ### Changes
@@ -10,7 +17,6 @@
 ### Fixes
 - Do not return media from trashed messages in the "All media" view. #4247
 
-
 ## [1.112.1] - 2023-03-27
 
 ### Changes

src/imex/transfer.rs

@@ -392,12 +392,10 @@ pub async fn get_backup(context: &Context, qr: Qr) -> Result<()> {
     let cancel_token = context.alloc_ongoing().await?;
     let res = tokio::select! {
         biased;
-        res = get_backup_inner(context, qr) => {
-            context.free_ongoing().await;
-            res
-        }
+        res = get_backup_inner(context, qr) => res,
         _ = cancel_token.recv() => Err(format_err!("cancelled")),
     };
+    context.free_ongoing().await;
     res
 }