diff --git a/src/sugar/bundle/activitybundle.py b/src/sugar/bundle/activitybundle.py
index 2c235d88..5f29a698 100644
--- a/src/sugar/bundle/activitybundle.py
+++ b/src/sugar/bundle/activitybundle.py
@@ -291,7 +291,7 @@ class ActivityBundle(Bundle):
         # List installed files
         manifestfiles = self.get_files(self._raw_manifest())
         paths  = []
-        for root, dirs, files in os.walk(install_path):
+        for root, dirs_, files in os.walk(install_path):
             rel_path = root[len(install_path) + 1:]
             for f in files:
                 paths.append(os.path.join(rel_path, f))
diff --git a/src/sugar/bundle/contentbundle.py b/src/sugar/bundle/contentbundle.py
index 32f38e30..f99c13a1 100644
--- a/src/sugar/bundle/contentbundle.py
+++ b/src/sugar/bundle/contentbundle.py
@@ -49,6 +49,7 @@ class ContentBundle(Bundle):
         self._category_icon = None
         self._library_version = None
         self._bundle_class = None
+        self._activity_start = None
 
         info_file = self.get_file('library/library.info')
         if info_file is None:
diff --git a/src/sugar/presence/activity.py b/src/sugar/presence/activity.py
index ab3cffff..bd41cecd 100644
--- a/src/sugar/presence/activity.py
+++ b/src/sugar/presence/activity.py
@@ -281,8 +281,8 @@ class Activity(gobject.GObject):
 
         def tubes_ready():
             if self.telepathy_text_chan is None or \
-                self.telepathy_tubes_chan is None:
-                    return
+               self.telepathy_tubes_chan is None:
+                return
 
             _logger.debug('%r: finished setting up tubes', self)
             reply_handler()
@@ -303,7 +303,7 @@ class Activity(gobject.GObject):
             found_text_channel = False
             found_tubes_channel = False
 
-            for chan_path, chan_iface, handle_type, handle in chans:
+            for chan_path, chan_iface, handle_type, handle_ in chans:
                 if handle_type != telepathy.HANDLE_TYPE_ROOM:
                     return
 
diff --git a/src/sugar/presence/presenceservice.py b/src/sugar/presence/presenceservice.py
index fb59a42b..50f0f7fd 100644
--- a/src/sugar/presence/presenceservice.py
+++ b/src/sugar/presence/presenceservice.py
@@ -178,7 +178,7 @@ class PresenceService(gobject.GObject):
                         self._del_object, object_path)
                 try:
                     # Pre-fill the activity's ID
-                    foo = obj.props.id
+                    activity_id = obj.props.id
                 except dbus.exceptions.DBusException:
                     logging.debug('Cannot get the activity ID')
             else:
@@ -239,9 +239,11 @@ class PresenceService(gobject.GObject):
         gobject.idle_add(self._emit_activity_invitation_signal, activity_path,
                          buddy_path, message)
 
-    def _emit_private_invitation_signal(self, bus_name, connection, channel, chan_type):
+    def _emit_private_invitation_signal(self, bus_name, connection,
+                                        channel, chan_type):
         """Emit GObject event with bus_name, connection and channel"""
-        self.emit('private-invitation', bus_name, connection, channel, chan_type)
+        self.emit('private-invitation', bus_name, connection,
+                  channel, chan_type)
         return False
 
     def _private_invitation_cb(self, bus_name, connection, channel, chan_type):
@@ -469,7 +471,7 @@ class PresenceService(gobject.GObject):
                       (activity.get_id(), err))
         self.emit("activity-shared", False, None, err)
 
-    def share_activity(self, activity, properties={}, private=True):
+    def share_activity(self, activity, properties=None, private=True):
         """Ask presence service to ask the activity to share itself publicly.
         
         Uses the AdvertiseActivity method on the service to ask for the 
@@ -484,6 +486,9 @@ class PresenceService(gobject.GObject):
         """
         actid = activity.get_id()
 
+        if properties is None:
+            properties = {}
+
         # Ensure the activity is not already shared/joined
         for obj in self._objcache.values():
             if not isinstance(object, Activity):
@@ -584,7 +589,7 @@ class _MockPresenceService(gobject.GObject):
     def get_owner(self):
         return None
 
-    def share_activity(self, activity, properties={}):
+    def share_activity(self, activity, properties=None):
         return None
 
 _ps = None
diff --git a/src/sugar/presence/sugartubeconn.py b/src/sugar/presence/sugartubeconn.py
index 34776119..18113fe1 100644
--- a/src/sugar/presence/sugartubeconn.py
+++ b/src/sugar/presence/sugartubeconn.py
@@ -19,8 +19,8 @@
 from telepathy.constants import (
     CHANNEL_GROUP_FLAG_CHANNEL_SPECIFIC_HANDLES)
 
-from tubeconn import TubeConnection
-import presenceservice
+from sugar.presence.tubeconn import TubeConnection
+from sugar.presence import presenceservice
 
 
 class SugarTubeConnection(TubeConnection):
diff --git a/src/sugar/profile.py b/src/sugar/profile.py
index 25b957ef..db360a1a 100644
--- a/src/sugar/profile.py
+++ b/src/sugar/profile.py
@@ -215,7 +215,7 @@ class Profile(object):
             return None
 
         # hash it
-        key_hash = util._sha_data(key)
+        key_hash = util.sha_data(key)
         return util.printable_hash(key_hash)
 
     def _get_privkey_hash(self):
diff --git a/src/sugar/util.py b/src/sugar/util.py
index a713cb0e..2706b5d6 100644
--- a/src/sugar/util.py
+++ b/src/sugar/util.py
@@ -31,7 +31,7 @@ def printable_hash(in_hash):
         printable = printable + binascii.b2a_hex(char)
     return printable
 
-def _sha_data(data):
+def sha_data(data):
     """sha1 hash some bytes."""
     sha_hash = sha.new()
     sha_hash.update(data)
@@ -52,7 +52,7 @@ def unique_id(data = ''):
         perfectly unique values.
     """
     data_string = "%s%s%s" % (time.time(), random.randint(10000, 100000), data)
-    return printable_hash(_sha_data(data_string))
+    return printable_hash(sha_data(data_string))
 
 
 ACTIVITY_ID_LEN = 40