build docker args with list.append

instead of constructing new list objects every time the list has items
appended to it, use python's list mutator functions (append and extend)

vmms/localDocker.py

@@ -156,15 +156,15 @@ def runJob(self, vm, runTimeout, maxOutputFileSize, disableNetwork):
                 os.getenv("DOCKER_TANGO_HOST_VOLUME_PATH"), instanceName
             )
         args = ["docker", "run", "--name", instanceName, "-v"]
-        args = args + ["%s:%s" % (volumePath, "/home/mount")]
+        args.append("%s:%s" % (volumePath, "/home/mount"))
         if vm.cores:
-            args = args + [f"--cpus={vm.cores}"]
+            args.append(f"--cpus={vm.cores}")
         if vm.memory:
-            args = args + ["-m", f"{vm.memory}m"]
+            args.extend(("-m", f"{vm.memory}m"))
         if disableNetwork:
-            args = args + ["--network", "none"]
-        args = args + [vm.image]
-        args = args + ["sh", "-c"]
+            args.append("--network", "none")
+        args.append(vm.image)
+        args.extend(("sh", "-c"))
 
         autodriverCmd = (
             "autodriver -u %d -f %d -t %d -o %d autolab > output/feedback 2>&1"
@@ -176,11 +176,11 @@ def runJob(self, vm, runTimeout, maxOutputFileSize, disableNetwork):
             )
         )
 
-        args = args + [
+        args.append(
             'cp -r mount/* autolab/; su autolab -c "%s"; \
                         cp output/feedback mount/feedback'
             % autodriverCmd
-        ]
+        )
 
         self.log.debug("Running job: %s" % str(args))
         ret = timeout(args, runTimeout * 2)