Extra "Email" column is removed.

It was added foolishly in revision c60680283888 whereas the very same column was there all the time :-(
diff --git a/app/soc/modules/gsoc/views/participants.py b/app/soc/modules/gsoc/views/participants.py
index 07dd305..d1aa86b 100644
--- a/app/soc/modules/gsoc/views/participants.py
+++ b/app/soc/modules/gsoc/views/participants.py
@@ -186,8 +186,6 @@
     list_config.addSimpleColumn('profile_id', 'Username')
     list_config.addPlainTextColumn(
         'email', 'Email', lambda entity, *args: entity.contact.email)
-    list_config.addPlainTextColumn(
-        'email', 'Email', lambda entity, *args: entity.contact.email)
     list_config.addSimpleColumn('gender', 'Gender', hidden=True)
     list_config.addSimpleColumn(
         'birth_date', 'Birthdate', column_type=lists.BIRTHDATE, hidden=True)