Try to ensure that Codecov always uploads a coverage report.

[seanlip]

Sometimes, Codecov fails to upload a coverage report. See e.g. #7621 (comment) -- Codecov did not block that PR as it couldn't upload the coverage report, causing the main codebase to have backend coverage failures.

The complete log at that time was:

Error: HTTPSConnectionPool(host='codecov.io', port=443): Max retries exceeded with url: /codecov/v4/raw/2019-09-17/6BBD04BAB28362906B7CAACFE0DF5AE7/0c88cf559bcb7f15a297dd3b26421857282fb475/15ca3dc1-2d7f-4cbd-be21-b934f7a34b39.txt?AWSAccessKeyId=AKIAIHLZSCQCS4WIHD4A&Expires=1568726448&Signature=ySd0BtSHoOpnjrvogq0fenmKChw%3D (Caused by NewConnectionError('<urllib3.connection.VerifiedHTTPSConnection object at 0x7ff4709c9890>: Failed to establish a new connection: [Errno 110] Connection timed out',))

The solution to this seems to be retrying till the coverage is uploaded successfully. Here is the context: link. The aim of this issue is to try this out in a PR.

[seanlip]

I think we've given up on Codecov (and are using CodeClimate instead for the primary check), so I'm closing this issue.