I've updated the debdiff to include a Breaks:  network-manager (<< 0.9.8.8-0ubuntu7.3) to ensure that users are forced to use the newer network-manager (ie, this libnl won't install unless user has already updated their network-manager)   Thanks Mathew for the suggestion.

I've built and tested this in the following way:

1. deploy trusty 14.04
2. apt-get install network-manager
3. download the libnl3 packages (3.2.21-1ubuntu2)
4. dpkg --install libnl-3-200_3.2.21-1ubuntu2_amd64.deb libnl-genl-3-200_3.2.21-1ubuntu2_amd64.deb libnl-route-3-200_3.2.21-1ubuntu2_amd64.deb 

This results in the following (successful blocking of upgrade):

dpkg: regarding libnl-3-200_3.2.21-1ubuntu2_amd64.deb containing libnl-3-200:amd64:
 libnl-3-200:amd64 breaks network-manager (<< 0.9.8.8-0ubuntu7.3)
  network-manager (version 0.9.8.8-0ubuntu7.2) is present and installed.

dpkg: error processing archive libnl-3-200_3.2.21-1ubuntu2_amd64.deb (--install):
 installing libnl-3-200:amd64 would break network-manager, and
 deconfiguration is not permitted (--auto-deconfigure might help)
(Reading database ... 37060 files and directories currently installed.)
Preparing to unpack libnl-genl-3-200_3.2.21-1ubuntu2_amd64.deb ...
Unpacking libnl-genl-3-200:amd64 (3.2.21-1ubuntu2) over (3.2.21-1) ...
Preparing to unpack libnl-route-3-200_3.2.21-1ubuntu2_amd64.deb ...
Unpacking libnl-route-3-200:amd64 (3.2.21-1ubuntu2) over (3.2.21-1) ...
dpkg: dependency problems prevent configuration of libnl-genl-3-200:amd64:
 libnl-genl-3-200:amd64 depends on libnl-3-200 (= 3.2.21-1ubuntu2); however:
  Version of libnl-3-200:amd64 on system is 3.2.21-1.

dpkg: error processing package libnl-genl-3-200:amd64 (--install):
 dependency problems - leaving unconfigured
dpkg: dependency problems prevent configuration of libnl-route-3-200:amd64:
 libnl-route-3-200:amd64 depends on libnl-3-200 (= 3.2.21-1ubuntu2); however:
  Version of libnl-3-200:amd64 on system is 3.2.21-1.

dpkg: error processing package libnl-route-3-200:amd64 (--install):
 dependency problems - leaving unconfigured
Errors were encountered while processing:
 libnl-3-200_3.2.21-1ubuntu2_amd64.deb
 libnl-genl-3-200:amd64
 libnl-route-3-200:amd64


After installing network-manager 0.9.8.8-0ubuntu7.3, I can successfully re-run the libnl3 install command:

dpkg --install libnl-3-200_3.2.21-1ubuntu2_amd64.deb libnl-genl-3-200_3.2.21-1ubuntu2_amd64.deb libnl-route-3-200_3.2.21-1ubuntu2_amd64.deb 
(Reading database ... 41021 files and directories currently installed.)
Preparing to unpack libnl-3-200_3.2.21-1ubuntu2_amd64.deb ...
Unpacking libnl-3-200:amd64 (3.2.21-1ubuntu2) over (3.2.21-1) ...
Selecting previously unselected package libnl-genl-3-200:amd64.
Preparing to unpack libnl-genl-3-200_3.2.21-1ubuntu2_amd64.deb ...
Unpacking libnl-genl-3-200:amd64 (3.2.21-1ubuntu2) ...
Selecting previously unselected package libnl-route-3-200:amd64.
Preparing to unpack libnl-route-3-200_3.2.21-1ubuntu2_amd64.deb ...
Unpacking libnl-route-3-200:amd64 (3.2.21-1ubuntu2) ...
Setting up libnl-3-200:amd64 (3.2.21-1ubuntu2) ...
Setting up libnl-genl-3-200:amd64 (3.2.21-1ubuntu2) ...
Setting up libnl-route-3-200:amd64 (3.2.21-1ubuntu2) ...
Processing triggers for libc-bin (2.19-0ubuntu6.6) ...