zdtmpy: Fix flake8 warnings

Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

test/zdtm.py

@@ -20,7 +20,6 @@ import fcntl
 import errno
 import datetime
 import yaml
-import socket
 import criu as crpc
 
 os.chdir(os.path.dirname(os.path.abspath(__file__)))
@@ -679,6 +678,7 @@ class criu_cli:
 		cr = subprocess.Popen(strace + [criu_bin, action] + args, env = env, preexec_fn = preexec)
 		return cr.wait()
 
+
 class criu_rpc:
 	@staticmethod
 	def __set_opts(criu, args, ctx):
@@ -730,7 +730,7 @@ class criu_rpc:
 		if action == 'dump':
 			criu.dump()
 		elif action == 'restore':
-			if not ctx.has_key('rd'):
+			if 'rd' not in ctx:
 				raise test_fail_exc('RPC Non-detached restore is impossible')
 
 			res = criu.restore()
@@ -745,6 +745,7 @@ class criu_rpc:
 			os.close(imgd)
 		return 0
 
+
 class criu:
 	def __init__(self, opts):
 		self.__test = None