conditions: fix criteria for 'or'

The criteria was wrongly set to None as the following code has
no return value:
  criteria = set().add(criteria)

We should do this instead:
  criteria = set([criteria])

Signed-off-by: Olivier Matz <olivier.matz@6wind.com>

diff --git a/imapami/conditions.py b/imapami/conditions.py
index 57014d9..4d06e88 100644 (file)
--- a/imapami/conditions.py
+++ b/imapami/conditions.py
@@ -676,7 +676,7 @@ class ImapamiCondOr(ImapamiCond):
             else:
                 criteria = 'OR (%s) (%s)' % (criteria, crit)
         if criteria != '':
-            criteria = set().add(criteria)
+            criteria = set([criteria])
         fetch = imapami.utils.highest_fetch_level(
             [c.fetch for c in cond_list])
         ImapamiCond.__init__(self, fetch=fetch, criteria=criteria)