agent: Use consistent naming for parameters to __exit__()

Using these specific names prevents Vulture from identifying these
parameters as unused.

monkey/infection_monkey/network/firewall.py

@@ -31,7 +31,7 @@ class FirewallApp(object):
     def __enter__(self):
         return self
 
-    def __exit__(self, exc_type, value, traceback):
+    def __exit__(self, _exc_type, value, traceback):
         self.close()
 
     def close(self):

monkey/infection_monkey/utils/auto_new_user.py

@@ -31,7 +31,7 @@ class AutoNewUser(metaclass=abc.ABCMeta):
         raise NotImplementedError()
 
     @abc.abstractmethod
-    def __exit__(self, exc_type, exc_val, exc_tb):
+    def __exit__(self, _exc_type, value, traceback):
         raise NotImplementedError()
 
     @abc.abstractmethod

monkey/infection_monkey/utils/linux/users.py

@@ -54,7 +54,7 @@ class AutoNewLinuxUser(AutoNewUser):
         )
         return subprocess.call(command_as_new_user)
 
-    def __exit__(self, exc_type, exc_val, exc_tb):
+    def __exit__(self, _exc_type, value, traceback):
         # delete the user.
         commands_to_delete_user = get_linux_commands_to_delete_user(self.username)
         logger.debug(

monkey/infection_monkey/utils/windows/users.py

@@ -111,7 +111,7 @@ class AutoNewWindowsUser(AutoNewUser):
     def get_logon_handle(self):
         return self.logon_handle
 
-    def __exit__(self, exc_type, exc_val, exc_tb):
+    def __exit__(self, _exc_type, value, traceback):
         # Logoff
         self.logon_handle.Close()