Remove <cond> and <val1> or <val2> systax

Use <val1> if <cond> else <val2> instead.
There're more talks:
[0] http://stackoverflow.com/questions/394809/ternary-conditional-operator-in-python
[1] http://www.python.org/dev/peps/pep-0308/

Fixes bug 1188111

Change-Id: I485e674317faf319a26ab30c2c193d8464a7e46e

swift/common/db.py

@@ -86,7 +86,7 @@ class GreenDBConnection(sqlite3.Connection):
     def __init__(self, *args, **kwargs):
         self.timeout = kwargs.get('timeout', BROKER_TIMEOUT)
         kwargs['timeout'] = 0
-        self.db_file = args and args[0] or '-'
+        self.db_file = args[0] if args else'-'
         sqlite3.Connection.__init__(self, *args, **kwargs)
 
     def _timeout(self, call):
@@ -591,7 +591,7 @@ class DatabaseBroker(object):
             try:
                 md = conn.execute('SELECT metadata FROM %s_stat' %
                                   self.db_type).fetchone()[0]
-                md = md and json.loads(md) or {}
+                md = json.loads(md) if md else {}
                 utf8encodekeys(md)
             except sqlite3.OperationalError, err:
                 if 'no such column: metadata' not in str(err):

swift/common/middleware/acl.py

@@ -110,7 +110,7 @@ def clean_acl(name, value):
                         raise ValueError('No host/domain value after referrer '
                                          'designation in ACL: %s' %
                                          repr(raw_value))
-                    values.append('.r:%s%s' % (negate and '-' or '', second))
+                    values.append('.r:%s%s' % ('-' if negate else '', second))
                 else:
                     raise ValueError('Unknown designator %s in ACL: %s' %
                                      (repr(first), repr(raw_value)))

swift/proxy/controllers/obj.py

@@ -979,7 +979,7 @@ class ObjectController(Controller):
             self.app.logger.error(
                 _('Object servers returned %s mismatched etags'), len(etags))
             return HTTPServerError(request=req)
-        etag = len(etags) and etags.pop() or None
+        etag = etags.pop() if len(etags) else None
         while len(statuses) < len(nodes):
             statuses.append(HTTP_SERVICE_UNAVAILABLE)
             reasons.append('')