feature: add thread local trace_id and trace_reason to logging. Added trace_id to default logging so that all logs for a given request share the same trace_id. This allows correlation of logs across a request. admin_guide.txt, upgrading.txt: add docs update sample configs to include trace_id. rewrite logging docs in admin_guide. Hopefully they are clearer now. clean up some stuff in the logging config file docs. admin.py: add decorators to run_command to enable trace_id. change calls to db.commit() to use run_command to get trace_id. configuration.py: clean up imports. update docstrings, comments and inline docs. add trace_id to default log format. add function for testing decorated with trace_id. add support for dumping stack trace in logging. add check for pytest in sys.modules to enable log propagation when pytest is running. Otherwise tests fail as the caplog logger doesn't see the roundup logs. logcontext.py: new file to handle thread local contextvar mangement. mailgw.py: add decorators for trace_id etc. scripts/roundup_xlmrpc_server.py: add decorators for trace_id etc. fix encoding bug turning bytes into a string. fix command line issue where we can't set encoding. (not sure if changing encoding via command line even works) cgi/client.py decorate two entry points for trace_id etc. cgi/wsgi_handler.py: decorate entry point for trace_id etc. test/test_config.py: add test for trace_id in new log format. test various cases for sinfo and errors in formating msg.

"""
In Python 3, sometimes TAL "python:" expressions that refer to
variables but not all variables are recognized. That is in Python 2.7
all variables used in a TAL "python:" expression are recognized as
references. In Python 3.5 (perhaps earlier), some TAL "python:"
expressions refer to variables but the reference generates an error
like this:

<class 'NameError'>: name 'some_tal_variable' is not defined

even when the variable is defined. Output after this message lists the
variable and its value.
"""

import unittest

from roundup.cgi.PageTemplates.PythonExpr import PythonExpr as PythonExprClass

class ExprTest(unittest.TestCase):
    def testExpr(self):
        expr = '[x for x in context.assignedto ' \
               'if x.realname not in user_realnames]'
        pe = PythonExprClass('test', expr, None)
        # Looking at the expression, only context and user_realnames are
        # external variables. The names assignedto and realname are members,
        # and x is local.
        required_names = ['context', 'user_realnames']
        got_names = pe._f_varnames
        for required_name in required_names:
            self.assertIn(required_name, got_names)