docker: updating image tag for devtool

We need to cross compile the fdt library for being
able to create Flattened Device Tree.
Also, a python test style warning was solved.

Signed-off-by: Diana Popa <[email protected]>

Author: dianpopa

tests/framework/jailer.py

@@ -230,5 +230,4 @@ def _kill_crgoup_tasks(self, controller):
         for task in tasks_split:
             if os.path.exists("/proc/{}".format(task)):
                 raise TimeoutError
-            else:
-                return True
+        return True

tools/devtool

@@ -73,7 +73,7 @@
 # Development container image (name:tag)
 # This should be updated whenever we upgrade the development container.
 # (Yet another step on our way to reproducible builds.)
-DEVCTR_IMAGE="fcuvm/dev:v5"
+DEVCTR_IMAGE="fcuvm/dev:v6"
 
 # Naming things is hard
 MY_NAME="Firecracker $(basename "$0")"