When the state of the interface changes rapidly enough (usually due to

rapid wireless association changes in my experience), there is a race
where dhclient is in the process of exiting due to the link going down
when the link coming up causes devd to try and start a new one.  This
results is the link being up, but no dhclient running.

Work around this race by checking a second time after a one second delay
before refusing to start a dhclient instance due to one already being
running.

MFC after:	1 week

etc/rc.d/dhclient

@@ -21,7 +21,11 @@ dhclient_start()
 	if [ -x /bin/pgrep ]; then
 		pids=`/bin/pgrep -f "dhclient: $ifn(\$| .*)"`
 		if [ -n "$pids" ]; then
-			exit 0
+			sleep 1
+			pids=`/bin/pgrep -f "dhclient: $ifn(\$| .*)"`
+			if [ -n "$pids" ]; then
+				exit 0
+			fi
 		fi
 	fi