Added 1.7.1 release notes for refs #23649.
Fixed #23469 -- Removed test runner compatibility check which often yielded false positives.
Fixed #23650 -- Prevented migrate from calling checks 3 times

Thanks Ilya Baryshev for the report and Tim Graham for the review.
Fixed #23676 -- Rearranged sentence; "by default" applies only to max length
Fixed #21196 -- Removed index on test field causing MySQL specific warning.
Fixed #23684 -- Used correct package name for Pillow in Error hint.
Fixed a typo in urlencode documentation.
Merge pull request #3390 from wrwrwr/fix/urlencode-ref-typo

Fixed a typo in urlencode documentation.
Prevented syncdb from calling system checks multiple times. Refs #23650.
Renamed skip_validation into skip_checks as the former is now deprecated.
Made the ping_google command override BaseCommand.handle() rather than execute().

Overriding execute() bypasses the system check framework among other things.