How to trigger a build for any branch in buildbot

I am using buildbot in a project and I have a setup of a scheduler, that automatically builds the project every time when there is a change, to test whether it compiles fine. This works and buildbot detects the changes on all branches but the scheduler always builds the master branch, no matter which branch the change is on. I want it to build the branch that the change is on but I have trouble making that work. Here are the relevant parts of the buildbot configuration:

GitPoller:

c['change_source'].append(GitPoller(
    repourl='git@git.somewhere.com:someproject.git',
    branches=True,
    pollinterval=60))

Scheduler:

c['schedulers'].append(AnyBranchScheduler(
    name='all',
    treeStableTimer=2*60,
    builderNames=['builder 1', 'builder 2']))

This is a helper function that I use on several builders to checkout the code. I am almost always calling it with no parameters. Using the parameter is a rare case for a specific branch, and the above scheduler does not run such a builder. I assume that when I use no parameters, I am always running in the else block:

def CheckoutFactory(whichBranch = ''):
    factory = BuildFactory()
    if whichBranch:
        factory.addStep(Git(repourl='git@git.somewhere.com:someproject.git', branch=whichBranch, mode='full', method='fresh', alwaysUseLatest=True, progress=True))
    else:
        factory.addStep(Git(repourl='git@git.somewhere.com:someproject.git', mode='full', method='fresh', alwaysUseLatest=True, progress=True))
    return factory

What is wrong here? Am I doing something wrong and how do I make buildbot run the builds on the branches with the changes?

Configuration:

The buildbot master is running on XUbuntu 16.04.1 64-bit.
The buildbot version is 0.8.12. (from the repos)
Git is version 2.7.4. (from the repos)

Solution

I've fixed it. It seems that is not as automatic as I had thought. The branch has to be passed to the Git step, using the value of the branch property. I did it like this:

factory.addStep(Git(repourl='git@git.somewhere.com:someproject.git', branch=WithProperties('%s', 'branch'), mode='full', method='fresh', alwaysUseLatest=True, progress=True))

The relevant change is that this parameter has been added:

branch=WithProperties('%s', 'branch')

I am using the deprecated WithProperties and not Propery because that would trigger this problem, and I didn't want to change my configuration too much.