Commit hashes differ from local and remote

[Arthur Debert <arthur@stimuli.com.br>]

Hi Folks.

I'm seeing some behavior that my git-fu isn't quite capable of explaining.

On a local branch the last commit has a hash different than the remote
branch it is tracking from. Nothing has been committed locally and
doing:
$ git diff branch-name origin/branch-name
Comes up empty
git pull also says my branch is already up to date.

It seems that git pull has generated a bogus commit (a merge commit),
but I can't quite figure out why.
This is specially important since we need our app servers to have the
same commit hash once git pull is done.

Anything obvious I'm missing out? Any extra info that can help
pinpoint what the issue is?

Thank you,
Arthur Debert