Remove argument "watch_log = "

This argument was marked deprecated in commit
I53fe014e80b507acf77a3c109179685e2e50200c,
Also there is no usage of argument watch_log in
other projects. It's safe to remove it now.

Change-Id: I49a6d9cf38957e661422f6175e86a5c3377d3b2d

neutron/agent/linux/daemon.py

@@ -22,7 +22,6 @@ import pwd
 import signal
 import sys
 
-from debtcollector import removals
 from oslo_log import log as logging
 
 from neutron._i18n import _
@@ -168,12 +167,9 @@ class Daemon(object):
 
     Usage: subclass the Daemon class and override the run() method
     """
-    @removals.removed_kwarg(
-        'watch_log',
-        message="Support for watch_log argument will be removed in Queens.")
     def __init__(self, pidfile, stdin=DEVNULL, stdout=DEVNULL,
                  stderr=DEVNULL, procname='python', uuid=None,
-                 user=None, group=None, watch_log=True):
+                 user=None, group=None):
         """Note: pidfile may be None."""
         self.stdin = stdin
         self.stdout = stdout
@@ -183,7 +179,6 @@ class Daemon(object):
                         if pidfile is not None else None)
         self.user = user
         self.group = group
-        self.watch_log = watch_log
 
     def _fork(self):
         try:
@@ -257,6 +252,5 @@ class Daemon(object):
 
         start() will call this method after the process has daemonized.
         """
-        if not self.watch_log:
-            unwatch_log()
+        unwatch_log()
         drop_privileges(self.user, self.group)