fix borg config --cache (make sure cache gets closed via try/finally)

src/borg/archiver.py

@@ -1774,6 +1774,7 @@ class Archiver:
             assert_secure(repository, manifest)
             cache = Cache(repository, key, manifest, lock_wait=self.lock_wait)
 
+        try:
             if args.cache:
                 cache.cache_config.load()
                 config = cache.cache_config._config
@@ -1802,10 +1803,10 @@ class Archiver:
                 except (configparser.NoOptionError, configparser.NoSectionError) as e:
                     print(e, file=sys.stderr)
                     return EXIT_WARNING
-
+            return EXIT_SUCCESS
+        finally:
             if args.cache:
                 cache.close()
-        return EXIT_SUCCESS
 
     def do_debug_info(self, args):
         """display system information for debugging / bug reports"""