python3: convert dict keys to a list

In Python 3.x, dict.keys() does not return a list, it returns an
iterable (specifically, a dictionary view). Use list(dict) to make code
compatible with both versions.

Part of #20

Author: ligurio

lib/tarantool_server.py

@@ -663,7 +663,7 @@ def __init__(self, _ini=None, test_suite=None):
         # or passed through execfile() for PythonTest
         self.current_test = None
         caller_globals = inspect.stack()[1][0].f_globals
-        if 'test_run_current_test' in caller_globals.keys():
+        if 'test_run_current_test' in list(caller_globals):
             self.current_test = caller_globals['test_run_current_test']
 
     def __del__(self):

lib/test_suite.py

@@ -185,7 +185,7 @@ def collect_tests(self):
         return self.tests
 
     def get_fragile_list(self):
-        return self.fragile['tests'].keys()
+        return list(self.fragile['tests'])
 
     def stable_tests(self):
         self.collect_tests()

lib/worker.py

@@ -287,7 +287,7 @@ def task_get(self, task_queue):
 
     @staticmethod
     def is_joinable(task_queue):
-        return 'task_done' in task_queue.__dict__.keys()
+        return 'task_done' in list(task_queue.__dict__)
 
     def restart_server(self):
         self.stop_server(cleanup=False)