stacktrace: include number of hidden frames

[blueyed]

Re-opening #1072.

TODO:

• bug (stacktrace: include number of hidden frames #1072 (comment))

  Traceback (most recent call last):                                                              
    File "/home/matthias/Projects/sites/***/venv/local/lib/python2.7/site-packages/django/core/handlers/exception.py", line 41, in inner
      response = get_response(request)                                                            
    File "/home/matthias/Projects/sites/***/venv/local/lib/python2.7/site-packages/django/utils/deprecation.py", line 142, in __call__
      response = self.process_response(request, response)
    File "/home/matthias/Projects/sites/***/venv/local/lib/python2.7/site-packages/debug_panel/middleware.py", line 67, in process_response
      panel.generate_stats(request, response)                                                                                                            
    File "/home/matthias/Projects/sites/***/venv/local/lib/python2.7/site-packages/debug_toolbar/panels/sql/panel.py", line 215, in generate_stats             
      query['stacktrace'] = render_stacktrace(query['stacktrace'])                                                                                                   
    File "/home/matthias/Projects/sites/***/venv/local/lib/python2.7/site-packages/debug_toolbar/utils.py", line 72, in render_stacktrace
      trace, hidden_count = trace           
  ValueError: too many values to unpack      
  

  trace contains a HTML string it seems.

[auvipy]

what issues does this need to be fixed

[blueyed]

what issues does this need to be fixed

IIRC this was meant as a placeholder/reminder for #1072, which was reverted back then. The issue this fixed/improved was to add an indicator for hidden frames.
Feel free to turn it into an issue (closing it for now).