Read_group() needs correction on query,

Install Accounting modules.
Go to Sales/Address Book /customers.

Click on (act_window) monthly turn over(which is a PSQL report).
Click on 'Events' or 'Related docs'(if knowledge is installed) afterwards.

Traceback:

Traceback (most recent call last):
  File "/home/jvo/workspace/trunk/server/bin/osv/osv.py", line 122, in wrapper
    return f(self, dbname, *args, **kwargs)
  File "/home/jvo/workspace/trunk/server/bin/osv/osv.py", line 176, in execute
    res = self.execute_cr(cr, uid, obj, method, *args, **kw)
  File "/home/jvo/workspace/trunk/server/bin/osv/osv.py", line 167, in execute_cr
    return getattr(object, method)(cr, uid, *args, **kw)
  File "/home/jvo/workspace/trunk/server/bin/osv/orm.py", line 2325, in read_group
    cr.execute('SELECT min(%s.id) AS id, count(%s.id) AS %s_count, ' % (self._table, self._table, group_count) + flist + ' FROM ' + from_clause + where_clause + gb + limit_str + offset_str, where_clause_params)
  File "/home/jvo/workspace/trunk/server/bin/sql_db.py", line 76, in wrapper
    return f(self, *args, **kwargs)
  File "/home/jvo/workspace/trunk/server/bin/sql_db.py", line 129, in execute
    res = self._obj.execute(query, params)
ProgrammingError: syntax error at or near "FROM"
LINE 1: ... AS id, count(res_partner_event.id) AS __count, FROM "res_...

The problem is with ',' just after __count.