can I always ignore a file during a merge?

Is there a way to merge from branchA to branchB and from branchB to branchA while completely ignoring changes to a file that is 
tracked and exists in both branches?

---- details ----

I have two branches in my project (master and energy2d)  automatically being built and tested on travis-ci:

   http://travis-ci.org/#!/concord-consortium/lab

When failures in tests occur notifications are sent to emails in a configuration file checked into each branch:

   master:
   https://github.com/concord-consortium/lab/blob/master/.travis.yml

   energy2d:
   https://github.com/concord-consortium/lab/blob/energy2d/.travis.yml

I regularly merge work in the energy2d branch into master and the Google Summero of Code student I am working with regularly 
merges changes in master into energy2d.

I would like to be able to merge both directions while completely ignoring changes in the travis-ci configuration files in each 
branch.

I have tried creating a .gitattributes file in each branch with the following content:

   .travis.yml merge=ours

But when interpreted by the default merge strategy "recursive" this only applies when there are conflicts -- however this 
current difference is not seen as a conflict:

   $ git diff energy2d .travis.yml
   diff --git a/.travis.yml b/.travis.yml
   index 8ea58dc..ec89f91 100644
   --- a/.travis.yml
   +++ b/.travis.yml
   @@ -8,7 +8,8 @@ notifications:
      email:
        recipients:
          - stephen.bannasch@gmail.com
   -      - janikpiotrek@gmail.com
   +      - sfentress@concord.org
   +      - rpk@pobox.com
    language: node_js
    node_js:
      - 0.6

Which means every time we merge the .travis.yml file is updated on the branch we are merging to.