Fix removing old backups

Author: mediaminister

lib/inputstreamhelper/widevine/widevine.py

@@ -192,7 +192,7 @@ def remove_old_backups(bpath):
     while len(versions) > max_backups + 1:
         remove_version = str(versions[1] if versions[0] == parse_version(installed_version) else versions[0])
         log(0, 'Removing oldest backup which is not installed: {version}', version=remove_version)
-        remove_tree(os.path.join(bpath, remove_version))
+        remove_tree(os.path.join(bpath, remove_version, ''))  # ensure trailing separator
         versions = sorted([parse_version(version) for version in listdir(bpath)])
 
     return