Update result.py

fix double []
diff --git a/staffeln/conductor/result.py b/staffeln/conductor/result.py
index eeb9c29..a76d99e 100644
--- a/staffeln/conductor/result.py
+++ b/staffeln/conductor/result.py
@@ -94,7 +94,7 @@
                 [

                     "Volume ID: %s, Reason: %s"

                     % (str(e["volume_id"]), str(e["reason"]))

-                    for e in self.failed_backup_list[[project["id"]]]

+                    for e in self.failed_backup_list[project["id"]]

                 ]

             )