[blink1073]

PYTHON-6262

Changes in this PR

Follow-up to #3218. I had forgotten to update the changelog entry after 4.20.0 was released.

Test Plan

Documentation-only change.

Checklist

Checklist for Author

• Did you update the changelog (if necessary)?
• Is there test coverage?
• Is any followup work tracked in a JIRA ticket? If so, add link(s). N/A

Checklist for Reviewer

• Does the title of the PR reference a JIRA Ticket?
• Do you fully understand the implementation? (Would you be comfortable explaining how this code works to someone else?)
• Is all relevant documentation (README or docstring) updated?
• Do the changes follow the MongoDB code standards? CODING-STANDARDS.md
• Have you considered the impact on the asynchronous API?

[Copilot]

🟡 Changes recommended

The diff includes runtime retry, integration-test, and CI changes despite a changelog-only scope, so it needs rebasing or an updated description and test plan covering those changes.

1 open issue

• Diff includes unplanned runtime, test, and CI changes · New

What changed in this PR

This follow-up to #3218 records the pinned getMore overload-retry fix under PyMongo 4.20.1 rather than 4.20.0. The supplied diff also includes the related driver, test, and CI changes.

Changes:

• Adds a 4.20.1 changelog section containing the PYTHON-6262 entry.
• Routes pinned operations through shared retry handling while preventing receive-only exhaust retries.
• Adds regression coverage and broadens load-balancer CI selection, with topology-specific test guards.

File	Description
test/​test_retryable_writes.py	Generated sync guard excluding the multi-mongos test in load-balanced mode.
test/​test_client_backpressure.py	Generated sync tests for pinned retries and exhaust error handling.
test/​asynchronous/​test_retryable_writes.py	Excludes the multi-mongos test in load-balanced mode.
test/​asynchronous/​test_client_backpressure.py	Tests pinned retry limits and receive-only exhaust failures.
test/​asynchronous/​__init__.py	Adds a server-capability guard for exhaust streaming tests.
test/​__init__.py	Generated sync exhaust-streaming test guard.
pymongo/​synchronous/​mongo_client.py	Generated sync pinned-connection retry handling.
pymongo/​mongo_client_shared.py	Stores the pinned connection manager in shared retry state.
pymongo/​asynchronous/​mongo_client.py	Integrates pinned connections into retries and guards exhaust receives.
doc/​changelog.rst	Records PYTHON-6262 under the new 4.20.1 section.
.evergreen/​scripts/​test_generate_config.py	Tests expanded load-balancer marker selection.
.evergreen/​scripts/​run_tests.py	Includes default suites alongside load-balancer-marked tests.

_{Review effort: Balanced}