Multiple pyperformance tests are incompatible with Python 3.9 #74

Changes in Python 3.9 break html5lib, django_template, and tornado_http tests with this error:

File "/usr/local/src/pyperf-tot-no-venv/lib/python3.9/site-packages/html5lib/_tokenizer.py", line 16, in <module> from ._trie import Trie File "/usr/local/src/pyperf-tot-no-venv/lib/python3.9/site-packages/html5lib/_trie/__init__.py", line 3, in <module> from .py import Trie as PyTrie File "/usr/local/src/pyperf-tot-no-venv/lib/python3.9/site-packages/html5lib/_trie/py.py", line 6, in <module> from ._base import Trie as ABCTrie File "/usr/local/src/pyperf-tot-no-venv/lib/python3.9/site-packages/html5lib/_trie/_base.py", line 3, in <module> from collections import Mapping ImportError: cannot import name 'Mapping' from 'collections' (/root/py3-tot-no/lib/python3.9/collections/__init__.py) ERROR: Benchmark html5lib failed: Benchmark died

How to reproduce the issue

I've been building Python 3 from source and encountered it through the standard build process.

1. Build Python from source. I produced with git commit befa032d8869e0fab4732d910f3887642879d644 from cpython GitHub.

2. Run pyperformance with one of the following parameter sets:

/py3buildpath/bin/pyperformance run --python=/py3buildpath/bin/python3 --venv venvpath -b html5lib -o output.json

/py3buildpath/bin/pyperformance run --python=/py3buildpath/bin/python3 --venv venvpath -b django_template -o output.json

/py3buildpath/bin/pyperformance run --python=/py3buildpath/bin/python3 --venv venvpath -b tornado_http -o output.json

3. Error message is shown.

What you expected to happen

I expected these pyperformance benchmark to complete successfully and produce a result (without error).

What actually happens

Benchmark dies trying to import from collections.

I believe with Python 3.9 these packages need to be directly imported from collections.abc.

See this commit: python/cpython@ef092fe

Here's a patch that was backported to the Python 3 vendored library: pypa/pip@ef7ca14#diff-2496ad1eedee846e323ed2916d6c2d24

This library probably needs an official release so that the vendored patch set in Python 3 doesn't become bloated.