After probably 02fad6a8 (component/{numpy,scipy}: Version up for Python3.)
pygolang test build started to fail in numpy compilation as shown in the
appendix. The failure is correct as pygolang never explicitly depended on
${numpy:egg}. We did not noticed before probably because in earlier versions
numpy did not required Cython to be present at install time.

-> Fix it by explicitly adding ${numpy:egg} to pygolang[all_test] dependencies.

Apendix. Log of test build failure

    networkcache: Trying to download pypi:numpy=1.22.0 from network cache...
    Getting distribution for 'numpy==1.22.0'.
    WARNING: The easy_install command is deprecated and will be removed in a future version.
    Running from numpy source directory.
    Processing numpy/random/_bounded_integers.pxd.in
    Processing numpy/random/_pcg64.pyx
    Traceback (most recent call last):
      File "/tmp/easy_install-z2of107_/numpy-1.22.0/tools/cythonize.py", line 53, in process_pyx
        import Cython
    ModuleNotFoundError: No module named 'Cython'

    The above exception was the direct cause of the following exception:

    Traceback (most recent call last):
      File "/tmp/easy_install-z2of107_/numpy-1.22.0/tools/cythonize.py", line 234, in <module>
        main()
      File "/tmp/easy_install-z2of107_/numpy-1.22.0/tools/cythonize.py", line 230, in main
        find_process_files(root_dir)
      File "/tmp/easy_install-z2of107_/numpy-1.22.0/tools/cythonize.py", line 221, in find_process_files
        process(root_dir, fromfile, tofile, function, hash_db)
      File "/tmp/easy_install-z2of107_/numpy-1.22.0/tools/cythonize.py", line 187, in process
        processor_function(fromfile, tofile)
      File "/tmp/easy_install-z2of107_/numpy-1.22.0/tools/cythonize.py", line 60, in process_pyx
        raise OSError(msg) from e
    OSError: Cython needs to be installed in Python as a module
    Traceback (most recent call last):
      File "/srv/slapgrid/slappart49/srv/runner/software/0919a77f026d6fc6870b3d6ec703b69d/eggs/setuptools-44.1.1-py3.9.egg/setuptools/sandbox.py", line 154, in save_modules
      File "/srv/slapgrid/slappart49/srv/runner/software/0919a77f026d6fc6870b3d6ec703b69d/eggs/setuptools-44.1.1-py3.9.egg/setuptools/sandbox.py", line 195, in setup_context
      File "<string>", line 7, in setup_context
      File "/srv/slapgrid/slappart49/srv/runner/software/0919a77f026d6fc6870b3d6ec703b69d/eggs/setuptools-44.1.1-py3.9.egg/setuptools/sandbox.py", line 250, in run_setup
      File "/srv/slapgrid/slappart49/srv/runner/software/0919a77f026d6fc6870b3d6ec703b69d/eggs/setuptools-44.1.1-py3.9.egg/setuptools/sandbox.py", line 45, in _execfile
      File "/tmp/easy_install-z2of107_/numpy-1.22.0/setup.py", line 450, in <module>
      File "/tmp/easy_install-z2of107_/numpy-1.22.0/setup.py", line 432, in setup_package
      File "/tmp/easy_install-z2of107_/numpy-1.22.0/setup.py", line 237, in generate_cython
    RuntimeError: Running cythonize failed!

    During handling of the above exception, another exception occurred:

    Traceback (most recent call last):
      File "<string>", line 10, in <module>
      File "/srv/slapgrid/slappart49/srv/runner/software/0919a77f026d6fc6870b3d6ec703b69d/eggs/setuptools-44.1.1-py3.9.egg/setuptools/command/easy_install.py", line 2317, in main
      File "/srv/slapgrid/slappart49/srv/runner/software/0919a77f026d6fc6870b3d6ec703b69d/eggs/setuptools-44.1.1-py3.9.egg/setuptools/__init__.py", line 162, in setup
      File "/srv/slapgrid/slappart49/srv/runner/shared/python3/a066243faa0ae8c256b7daa6207cc9a6/lib/python3.9/distutils/core.py", line 148, in setup
        dist.run_commands()
      File "/srv/slapgrid/slappart49/srv/runner/shared/python3/a066243faa0ae8c256b7daa6207cc9a6/lib/python3.9/distutils/dist.py", line 966, in run_commands
        self.run_command(cmd)
      File "/srv/slapgrid/slappart49/srv/runner/shared/python3/a066243faa0ae8c256b7daa6207cc9a6/lib/python3.9/distutils/dist.py", line 985, in run_command
        cmd_obj.run()
      File "/srv/slapgrid/slappart49/srv/runner/software/0919a77f026d6fc6870b3d6ec703b69d/eggs/setuptools-44.1.1-py3.9.egg/setuptools/command/easy_install.py", line 424, in run
      File "/srv/slapgrid/slappart49/srv/runner/software/0919a77f026d6fc6870b3d6ec703b69d/eggs/setuptools-44.1.1-py3.9.egg/setuptools/command/easy_install.py", line 666, in easy_install
      File "/srv/slapgrid/slappart49/srv/runner/software/0919a77f026d6fc6870b3d6ec703b69d/eggs/setuptools-44.1.1-py3.9.egg/setuptools/command/easy_install.py", line 711, in install_item
      File "/srv/slapgrid/slappart49/srv/runner/software/0919a77f026d6fc6870b3d6ec703b69d/eggs/setuptools-44.1.1-py3.9.egg/setuptools/command/easy_install.py", line 896, in install_eggs
      File "/srv/slapgrid/slappart49/srv/runner/software/0919a77f026d6fc6870b3d6ec703b69d/eggs/setuptools-44.1.1-py3.9.egg/setuptools/command/easy_install.py", line 1164, in build_and_install
      File "/srv/slapgrid/slappart49/srv/runner/software/0919a77f026d6fc6870b3d6ec703b69d/eggs/setuptools-44.1.1-py3.9.egg/setuptools/command/easy_install.py", line 1150, in run_setup
      File "/srv/slapgrid/slappart49/srv/runner/software/0919a77f026d6fc6870b3d6ec703b69d/eggs/setuptools-44.1.1-py3.9.egg/setuptools/sandbox.py", line 253, in run_setup
      File "/srv/slapgrid/slappart49/srv/runner/shared/python3/a066243faa0ae8c256b7daa6207cc9a6/lib/python3.9/contextlib.py", line 137, in __exit__
        self.gen.throw(typ, value, traceback)
      File "<string>", line 7, in setup_context
      File "/srv/slapgrid/slappart49/srv/runner/shared/python3/a066243faa0ae8c256b7daa6207cc9a6/lib/python3.9/contextlib.py", line 137, in __exit__
        self.gen.throw(typ, value, traceback)
      File "/srv/slapgrid/slappart49/srv/runner/software/0919a77f026d6fc6870b3d6ec703b69d/eggs/setuptools-44.1.1-py3.9.egg/setuptools/sandbox.py", line 195, in setup_context
      File "/srv/slapgrid/slappart49/srv/runner/shared/python3/a066243faa0ae8c256b7daa6207cc9a6/lib/python3.9/contextlib.py", line 137, in __exit__
        self.gen.throw(typ, value, traceback)
      File "/srv/slapgrid/slappart49/srv/runner/software/0919a77f026d6fc6870b3d6ec703b69d/eggs/setuptools-44.1.1-py3.9.egg/setuptools/sandbox.py", line 166, in save_modules
      File "/srv/slapgrid/slappart49/srv/runner/software/0919a77f026d6fc6870b3d6ec703b69d/eggs/setuptools-44.1.1-py3.9.egg/setuptools/sandbox.py", line 141, in resume
      File "/srv/slapgrid/slappart49/srv/runner/software/0919a77f026d6fc6870b3d6ec703b69d/eggs/setuptools-44.1.1-py3.9.egg/setuptools/_vendor/six.py", line 685, in reraise
      File "/srv/slapgrid/slappart49/srv/runner/software/0919a77f026d6fc6870b3d6ec703b69d/eggs/setuptools-44.1.1-py3.9.egg/setuptools/sandbox.py", line 154, in save_modules
      File "/srv/slapgrid/slappart49/srv/runner/software/0919a77f026d6fc6870b3d6ec703b69d/eggs/setuptools-44.1.1-py3.9.egg/setuptools/sandbox.py", line 195, in setup_context
      File "<string>", line 7, in setup_context
      File "/srv/slapgrid/slappart49/srv/runner/software/0919a77f026d6fc6870b3d6ec703b69d/eggs/setuptools-44.1.1-py3.9.egg/setuptools/sandbox.py", line 250, in run_setup
      File "/srv/slapgrid/slappart49/srv/runner/software/0919a77f026d6fc6870b3d6ec703b69d/eggs/setuptools-44.1.1-py3.9.egg/setuptools/sandbox.py", line 45, in _execfile
      File "/tmp/easy_install-z2of107_/numpy-1.22.0/setup.py", line 450, in <module>
      File "/tmp/easy_install-z2of107_/numpy-1.22.0/setup.py", line 432, in setup_package
      File "/tmp/easy_install-z2of107_/numpy-1.22.0/setup.py", line 237, in generate_cython
    RuntimeError: Running cythonize failed!
    Cythonizing sources
    An error occurred when trying to install numpy 1.22.0. Look above this message for any errors that were output by easy_install.
    While:
      Installing gpython.
      Base installation request: 'pygolang[all_test]'
        Requirement of pygolang[all_test]: wheel
        Requirement of pygolang[all_test]: setuptools_dso>=2.8
        Requirement of pygolang[all_test]: setuptools
        Requirement of pygolang[all_test]: pytest
        Requirement of pygolang[all_test]: numpy
        Requirement of pygolang[all_test]: ipython
        Requirement of pygolang[all_test]: cython<3
        Requirement of pygolang[all_test]: geventmp
        Requirement of pygolang[all_test]: setuptools_dso>=2.8
        Requirement of pygolang[all_test]: decorator
        Requirement of pygolang[all_test]: six
        Requirement of pygolang[all_test]: gevent
        Requirement of setuptools_dso>=2.8: setuptools
        Requirement of pytest: wcwidth
        Requirement of pytest: six>=1.10.0
        Requirement of pytest: py>=1.5.0
        Requirement of pytest: pluggy<1.0,>=0.12
        Requirement of pytest: packaging
        Requirement of pytest: more-itertools>=4.0.0
        Requirement of pytest: attrs>=17.4.0
        Requirement of pytest: atomicwrites>=1.0
      Getting distribution for 'numpy==1.22.0'.
    Error: Couldn't install: numpy 1.22.0