Fix closes Issue12183 - Explain the Symlink copy behavior in shutil.copytree. Patch by Petri Lehtinen.

Reported by Popa Claudiu and Patch by Santoso Wijaya.

Reported by Popa Claudiu and Patch by Santoso Wijaya.

Also, add an entry for the script in Tools/scripts/README.

Issue #11049: fix test_forget to work on installed Python, by using a temporary module for import/forget

See: https://bugzilla.redhat.com/show_bug.cgi?id=726536

This will be particularly useful to Windows users.

run_tests.py originally written by Brett Cannon.

This prevents tests from failing when run from a Python installed in a
read-only directory.  The code is a bit uglier; shutil.copytree calls
copystat on directories behind our back, so I had to add an os.walk
with os.chmod (*and* os.path.join!) calls.  shutil, I am disappoint.

This changeset is dedicated to the hundreds of neurons that were lost
while I was debugging this on an otherwise fine afternoon.

This prevents tests from failing when run from a Python installed in a
read-only directory.

Code extracted from Victor Stinner's patch for issue #12567.

The changed behavior of sdist in 3.1 broke packaging for projects that
wanted to use a manually-maintained MANIFEST file (instead of having a
MANIFEST.in template and letting distutils generate the MANIFEST).

The fixes that were committed for #8688 (76643c286b9f by Tarek and
d54da9248ed9 by me) did not fix all issues exposed in the bug report,
and also added one problem: the MANIFEST file format gained comments,
but the read_manifest method was not updated to handle (i.e. ignore)
them.  This changeset should fix everything; the tests have been
expanded and I successfully tested the 2.7 version with Mercurial, which
suffered from this regression.

I have grouped the versionchanged directives for these bugs in one place
and added micro version numbers to help users know the quirks of the
exact version they’re using.

Initial report, thorough diagnosis and patch by John Dennis, further
work on the patch by Stephen Thorne, and a few edits and additions by
me.