Issue initializing MOE

[1Reinier]

After starting MOE like this on El Capitan (Python 2.7.11 Anaconda, MOE built with gcc 5.3.0):

system:MOE user$ pserve --reload development.ini 

MOE tests fail with the following error:

Starting subprocess with file monitor
Traceback (most recent call last):
  File "/Users/user/anaconda/envs/py27/bin/pserve", line 11, in <module>
    sys.exit(main())
  File "/Users/user/anaconda/envs/py27/lib/python2.7/site-packages/pyramid/scripts/pserve.py", line 51, in main
    return command.run()
  File "/Users/user/anaconda/envs/py27/lib/python2.7/site-packages/pyramid/scripts/pserve.py", line 316, in run
    global_conf=vars)
  File "/Users/user/anaconda/envs/py27/lib/python2.7/site-packages/pyramid/scripts/pserve.py", line 340, in loadapp
    return loadapp(app_spec, name=name, relative_to=relative_to, **kw)
  File "/Users/user/anaconda/envs/py27/lib/python2.7/site-packages/paste/deploy/loadwsgi.py", line 247, in loadapp
    return loadobj(APP, uri, name=name, **kw)
  File "/Users/user/anaconda/envs/py27/lib/python2.7/site-packages/paste/deploy/loadwsgi.py", line 272, in loadobj
    return context.create()
  File "/Users/user/anaconda/envs/py27/lib/python2.7/site-packages/paste/deploy/loadwsgi.py", line 710, in create
    return self.object_type.invoke(self)
  File "/Users/user/anaconda/envs/py27/lib/python2.7/site-packages/paste/deploy/loadwsgi.py", line 203, in invoke
    app = context.app_context.create()
  File "/Users/user/anaconda/envs/py27/lib/python2.7/site-packages/paste/deploy/loadwsgi.py", line 710, in create
    return self.object_type.invoke(self)
  File "/Users/user/anaconda/envs/py27/lib/python2.7/site-packages/paste/deploy/loadwsgi.py", line 146, in invoke
    return fix_call(context.object, context.global_conf, **context.local_conf)
  File "/Users/user/anaconda/envs/py27/lib/python2.7/site-packages/paste/deploy/util.py", line 58, in fix_call
    reraise(*exc_info)
  File "/Users/user/anaconda/envs/py27/lib/python2.7/site-packages/paste/deploy/compat.py", line 23, in reraise
    exec('raise t, e, tb', dict(t=t, e=e, tb=tb))
  File "/Users/user/anaconda/envs/py27/lib/python2.7/site-packages/paste/deploy/util.py", line 55, in fix_call
    val = callable(*args, **kw)
  File "/Users/user/anaconda/envs/py27/lib/python2.7/site-packages/moe/__init__.py", line 40, in main
    'moe.tests',
  File "/Users/user/anaconda/envs/py27/lib/python2.7/site-packages/pyramid/config/__init__.py", line 930, in scan
    ignore=ignore)
  File "/Users/user/anaconda/envs/py27/lib/python2.7/site-packages/venusian/__init__.py", line 205, in scan
    __import__(modname)
  File "/Users/user/anaconda/envs/py27/lib/python2.7/site-packages/moe/optimal_learning/python/cpp_wrappers/domain.py", line 10, in <module>
    import moe.build.GPP as C_GP
TypeError: No registered converter was able to produce a C++ rvalue of type std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > from this Python object of type str

I did not encounter any errors during building and I also made sure all the requirements are in place.
How can I resolve this issue? Could it be related to my gcc version?