The problem you have is likely due to incompatible compilers being used to build the Python you want to use and ROOT, or the wrong library being loaded at runtime. Your Python was built with [GCC 4.2.1 Compatible Apple LLVM 9.1.0 (clang-902.0.39.1)] as indicated above. In order for ROOT to work with Python, you must build ROOT with the same compiler that was used to build Python. Also, you must ensure that the library paths are such that the right Python library is found first, unless you use RPATH to link (option -Drpath=ON in CMake). It could be that you built against Python 2.7.15, but the library being loaded at runtime is still from Python 2.7.10, in which case it will not work. When configuring, I recommend to use CMake, and pass only -DPYTHON_EXECUTABLE=/usr/local/bin/python when configuring. Also, check that all python libraries are picked for the correct version of Python. For example, in my machine, I get:
-- Found PythonInterp: /usr/bin/python3.6 (found version "3.6.5")
-- Found PythonLibs: /usr/lib/libpython3.6m.so (found version "3.6.5")
-- Found NUMPY: /usr/lib64/python3.6/site-packages/numpy/core/include (found version "1.13.3")
when using cmake ~/src/root -DPYTHON_EXECUTABLE=$(which python3.6). In your case, you should see found version 2.7.15 both for the interpreter and libraries.