Log messages when permission checks fail rather than traceback

[Ryan J Ollos]

Looking in the log files I see many entries like the following:

2014-05-28 12:13:22,695 Trac[web_ui] ERROR: RPC(XML-RPC) Error
Traceback (most recent call last):
  File "build/bdist.linux-x86_64/egg/tracrpc/web_ui.py", line 149, in _rpc_process
    req.perm.require('XML_RPC') # Need at least XML_RPC
  File "/usr/local/python26_trac10/lib/python2.6/site-packages/Trac-1.0.1-py2.6.egg/trac/perm.py", line 579, in require
    raise PermissionError(action, resource, self.env)
PermissionError

Web requests on the other hand are ​trapped and ​logged:

2014-05-28 17:01:26,569 Trac[main] WARNING: [12.234.78.2] HTTPForbidden: 403 Forbidden (WIKI_VIEW privileges are required to perform this operation on WikiStart. You don't have the required permissions.)

I'm wondering if we could trap and log XmlRpc requests as warnings. I haven't done more than look at the code yet, but I could probably propose a patch.

See also #12408.