python3 incompatibility

[Shaana]

Running python-for-android (master) with 'python3crystax' and 'storm' requirements fails, even though the 'storm' recipe is specified to run with python3.

/usr/bin/python -m pythonforandroid.toolchain create --dist_name=testApp --bootstrap=sdl2 --requirements=python3crystax,kivy==master,sqlite3,storm --arch armeabi-v7a --copy-libs --color=always --storage-dir=/home/shaana/development/test1/src/.buildozer/android/platform/build

[INFO]:    Building storm for armeabi-v7a
[INFO]:    storm apparently isn't already in site-packages
Traceback (most recent call last):
  File "/usr/lib/python2.7/runpy.py", line 174, in _run_module_as_main
    "__main__", fname, loader, pkg_name)
  File "/usr/lib/python2.7/runpy.py", line 72, in _run_code
    exec code in run_globals
  File "/home/shaana/development/test1/src/.buildozer/android/platform/python-for-android-master/pythonforandroid/toolchain.py", line 992, in <module>
    main()
  File "/home/shaana/development/test1/src/.buildozer/android/platform/python-for-android-master/pythonforandroid/toolchain.py", line 989, in main
    ToolchainCL()
  File "/home/shaana/development/test1/src/.buildozer/android/platform/python-for-android-master/pythonforandroid/toolchain.py", line 526, in __init__
    getattr(self, args.subparser_name.replace('-', '_'))(args)
  File "/home/shaana/development/test1/src/.buildozer/android/platform/python-for-android-master/pythonforandroid/toolchain.py", line 149, in wrapper_func
    build_dist_from_args(ctx, dist, args)
  File "/home/shaana/development/test1/src/.buildozer/android/platform/python-for-android-master/pythonforandroid/toolchain.py", line 194, in build_dist_from_args
    build_recipes(build_order, python_modules, ctx)
  File "pythonforandroid/build.py", line 574, in build_recipes
    recipe.build_arch(arch)
  File "pythonforandroid/recipe.py", line 806, in build_arch
    self.install_python_package(arch)
  File "pythonforandroid/recipe.py", line 815, in install_python_package
    env = self.get_recipe_env(arch)
  File "pythonforandroid/recipe.py", line 786, in get_recipe_env
    hppath += [join(builddir, d) for d in listdir(builddir)
OSError: [Errno 2] No such file or directory: 'build'

Removing the following lines from the recipe might solve the issue.

    call_hostpython_via_targetpython = False
    install_in_hostpython = True

There are probably other recipes with the same issue.

[AndreMiras]

I also came across that issue when working on a fix for #1245. So I might pick it up next.
@Shaana, @inclement do you have any hint?
Edit: fixed in #1249