

An edge case is when the python is provided by a part that does not need to install anything.

>>> import sys
>>> print(system(buildout, env={'PYTHONWARNINGS':'ignore'}))
Develop: '/sample-buildout/recipes'
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>>> write(sample_buildout, 'buildout.cfg',
... """
... [buildout]
... develop = recipes
... extensions = slapos.rebootstrap
... python = already_installed_python
...
... parts =
...   realrun
...
... [already_installed_python]
... recipe = recipes:pyalreadyinstalled
...
... [realrun]
... recipe = recipes:pyshow
... """ % dict(syspython=sys.executable))

>>> print(system(buildout, env={'PYTHONWARNINGS':'ignore'}))
Using already installed /system_python
Develop: '/sample-buildout/recipes'
Installing already_installed_python.
Installing realrun.
Running with: /system_python
<BLANKLINE>
