[Python-Dev] PEP 405 (venv) - why does it copy the DLLs on Windows

[Paul Moore]

PEP 405 has this note:

"""
On Windows, it is necessary to also copy or symlink DLLs and pyd files
from compiled stdlib modules into the env, because if the venv is
created from a non-system-wide Python installation, Windows won't be
able to find the Python installation's copies of those files when
Python is run from the venv.
"""

I don't understand what this is saying - can someone clarify the
reason behind this statement? What is different about a
"non-system-wide installation" that causes this issue (I assume
"non-system-wide" means "not All Users")? The reason I ask is that
virtualenv doesn't do this, and I'm not clear if this is because of a
potential bug lurking in virtualenv (in which case, I'd like to find
out how to reproduce it) or because virtualenv takes a different
approach which avoids this issue somehow.

Thanks,
Paul.