Verifying for precise.
I fully updated all the meta packages. And I also removed all the old meta packages.
I only kept a couple of old kernels around.
Then, the previous update-manager-core version produced an empty apt line,
while the newer one didn't.

Exact output:

# dpkg-query -W update-manager-core
update-manager-core    1:0.156.14.17

# hwe-support-status 
Your current Hardware Enablement Stack (HWE) is no longer supported
since 2014-08-07.  Security updates for critical parts (kernel
and graphics stack) of your system are no longer available.
For more information, please see:
http://wiki.ubuntu.com/1204_HWE_EOL
To upgrade to a supported (or longer supported) configuration:
* Upgrade from Ubuntu 12.04 LTS to Ubuntu 14.04 LTS by running:
sudo do-release-upgrade 
OR
* Install a newer HWE version by running:
sudo apt-get install 
and reboot your system.

# dpkg -l '*linux*'|grep ^ii
ii  libselinux1                                 2.1.0-4.1ubuntu1                    SELinux runtime shared libraries
ii  linux-firmware                              1.79.9                              Firmware for Linux kernel drivers
ii  linux-generic-lts-trusty                    3.13.0.46.40                        Generic Linux kernel image and headers
ii  linux-headers-3.11.0-15                     3.11.0-15.25~precise1               Header files related to Linux kernel version 3.11.0
ii  linux-headers-3.11.0-15-generic             3.11.0-15.25~precise1               Linux kernel headers for version 3.11.0 on 64 bit x86 SMP
ii  linux-headers-3.13.0-46                     3.13.0-46.75~precise1               Header files related to Linux kernel version 3.13.0
ii  linux-headers-3.13.0-46-generic             3.13.0-46.75~precise1               Linux kernel headers for version 3.13.0 on 64 bit x86 SMP
ii  linux-headers-generic-lts-trusty            3.13.0.46.40                        Generic Linux kernel headers
ii  linux-image-3.11.0-15-generic               3.11.0-15.25~precise1               Linux kernel image for version 3.11.0 on 64 bit x86 SMP
ii  linux-image-3.13.0-46-generic               3.13.0-46.75~precise1               Linux kernel image for version 3.13.0 on 64 bit x86 SMP
ii  linux-image-generic-lts-trusty              3.13.0.46.40                        Generic Linux kernel image
ii  linux-libc-dev                              3.2.0-58.88                         Linux Kernel Headers for development
ii  linux-sound-base                            1.0.25+dfsg-0ubuntu1.1              base package for ALSA and OSS sound systems
ii  pptp-linux                                  1.7.2-6                             Point-to-Point Tunneling Protocol (PPTP) Client
ii  syslinux                                    2:4.05+dfsg-2                       collection of boot loaders
ii  syslinux-common                             2:4.05+dfsg-2                       collection of boot loaders (common files)
ii  syslinux-legacy                             2:3.63+dfsg-2ubuntu5                Bootloader for Linux/i386 using MS-DOS floppies
ii  util-linux                                  2.20.1-1ubuntu3                     Miscellaneous system utilities

After updating to .18:

# hwe-support-status 
Your current Hardware Enablement Stack (HWE) is no longer supported
since 2014-08-07.  Security updates for critical parts (kernel
and graphics stack) of your system are no longer available.
For more information, please see:
http://wiki.ubuntu.com/1204_HWE_EOL
The following packages are no longer supported:
 linux-headers-3.11.0-15 linux-headers-3.11.0-15-generic linux-image-3.11.0-15-generic
Please upgrade them to a supported HWE stack or remove them if you
no longer need them.