dhclient keeps trying to make DHCP requests even after the NetworkManager service has been stopped

Issue

• Logs are full of dhclient messages. NetworkManager has been stopped and no interface is set to use DHCP:

$ grep dhclient /var/log/messages | tail
May 16 12:06:09 localhost dhclient[12549]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 5 (xid=0x1e4b774e)
May 16 12:06:14 localhost dhclient[12549]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 11 (xid=0x1e4b774e)
May 16 12:06:25 localhost dhclient[12549]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 13 (xid=0x1e4b774e)
May 16 12:06:38 localhost dhclient[12549]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 15 (xid=0x1e4b774e)
May 16 12:06:53 localhost dhclient[12549]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 14 (xid=0x1e4b774e)
May 16 12:07:07 localhost dhclient[12549]: No DHCPOFFERS received.
May 16 12:07:07 localhost dhclient[12549]: No working leases in persistent database - sleeping.
May 16 12:13:37 localhost dhclient[12549]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 7 (xid=0xe85bfcc)
May 16 12:13:44 localhost dhclient[12549]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 7 (xid=0xe85bfcc)
May 16 12:13:51 localhost dhclient[12549]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 15 (xid=0xe85bfcc)