Refactor client.py session cookie code. Remove session db access. The original code did a session_db.exists test followed by a session_db.getall. Refactor does a getall and if a KeyError is thrown, handles the error. Most likely the session key will be found so exception handling won't be triggered. Added test case to test the exception code path and minor rearrangement of setup code.

#!/usr/bin/env python

# Roundup requires Python 2.7+ as mentioned in doc\installation.txt
from __future__ import print_function
import sys

VERSION_NEEDED = (2, 7)

if sys.version_info < VERSION_NEEDED:
    print("Content-Type: text/plain\n")
    print("Roundup requires Python %s.%s or newer." % VERSION_NEEDED)
    sys.exit(0)