IntegrityError: (1062, "Duplicate entry 'bd59677900e7b89-0-timeline.daysback' for key 1")

I frequently see this error when accessing the trac timeline.

How to Reproduce

While doing a GET operation on /timeline, Trac issued an internal error.

''(please provide additional details here)''

System Information

|| Trac || 0.11.1 ||

|| Python || 2.4.3 (#1, May 24 2008, 13:47:28) [GCC 4.1.2 20070626 (Red Hat 4.1.2-14)] ||

|| setuptools || 0.6c5 ||

|| MySQL || server: "5.0.45", client: "5.0.45", thread-safe: 0 ||

|| MySQLdb || 1.2.2 ||

|| Genshi || 0.5.1 ||

|| mod_python || 3.2.8 ||

|| Subversion || 1.4.2 (r22196) ||

Python Traceback

Traceback (most recent call last):
  File "/usr/lib/python2.4/site-packages/Trac-0.11.1-py2.4.egg/trac/web/main.py", line 423, in _dispatch_request
    dispatcher.dispatch(req)
  File "/usr/lib/python2.4/site-packages/Trac-0.11.1-py2.4.egg/trac/web/main.py", line 222, in dispatch
    req.session.save()
  File "/usr/lib/python2.4/site-packages/Trac-0.11.1-py2.4.egg/trac/web/session.py", line 102, in save
    "VALUES(%s,%s,%s,%s)", attrs)
  File "/usr/lib/python2.4/site-packages/Trac-0.11.1-py2.4.egg/trac/db/util.py", line 57, in executemany
    return self.cursor.executemany(sql_escape_percent(sql), args)
  File "build/bdist.linux-i686/egg/MySQLdb/cursors.py", line 218, in executemany
  File "build/bdist.linux-i686/egg/MySQLdb/cursors.py", line 312, in _query
  File "build/bdist.linux-i686/egg/MySQLdb/cursors.py", line 276, in _do_query
IntegrityError: (1062, "Duplicate entry 'bd59677900e7b89-0-timeline.daysback' for key 1")