installation of older Mako easyconfigs broken because MarkupSafe 2.0.0a1 is picked up

[boegel]

For example, Mako-1.0.7-intel-2018a-Python-2.7.14.eb fails with:

== 2020-04-23 14:17:13,104 build_log.py:169 ERROR EasyBuild crashed with an error (at easybuild/base/exceptions.py:124 in __init__): cmd " /software/Python/2.7.14-intel-2018a/bin/python setup.py install --prefix=/software/Mako/1.0.7-intel-2018a-Python-2.7.14 " exited with exit code 1 and output:
...
Processing dependencies for Mako==1.0.7
Searching for MarkupSafe>=0.9.2
Reading https://pypi.python.org/simple/MarkupSafe/
Downloading https://files.pythonhosted.org/packages/e0/bf/acc45baeb2d7333ed724c30af188640d9cb0be4b28533edfc3e2ae5aad72/MarkupSafe-2.0.0a1.tar.gz#sha256=beac28ed60c8e838301226a7a85841d0af2068eba2dcb1a58c2d32d6c05e440e
Best match: MarkupSafe 2.0.0a1
Processing MarkupSafe-2.0.0a1.tar.gz
...
ImportError: No module named markupsafe

Can be fixed relatively easy by making the broken Mako easyconfigs use PythonBundle, and adding MarkupSafe 1.1.1 as an extension in them.

This doesn't affect recent Mako easyconfigs like Mako-1.0.8-GCCcore-8.2.0.eb & newer, because the underlying Python already includes MarkupSafe 1.1.1