checkout@v2 does no retries when failing to download submodules

[murgatroid99]

I have a repository with a number of submodules transitively included. I created a job with this step:

- uses: actions/checkout@v2
  with:
    submodules: recursive

In one job run I got this failure:

##[error]fatal: unable to access 'https://github.com/google/googletest.git/': Failed to connect to github.com port 443: Operation timed out
Fetched in submodule path 'packages/grpc-native-core/deps/grpc/third_party/bloaty/third_party/googletest', but it did not contain a2b8a8e07628e5fd60644b6dd99c1b5e7d7f1f47. Direct fetching of that commit failed.

I didn't see any retries or other attempts to recover from the failure. This caused the step to fail, which caused the whole job to fail. It is part of a large matrix so restarting the whole workflow for this is painful.

The full log for this failure can be found at https://github.com/grpc/grpc-node/runs/665059836?check_suite_focus=true

[murgatroid99]

There is another example with more failures in this log: https://github.com/grpc/grpc-node/pull/1409/checks?check_run_id=667975279

[alexey-milovidov]

We have this issue with ClickHouse repository: https://github.com/ClickHouse/ClickHouse/runs/4513286245?check_suite_focus=true