non-protocol=v2 clonable submodules can fail a checkout

[asottile]

for example:

fetch attempt 1...
    => success
submodule checkout attempt 1...
    => error
    error: Server does not allow request for unadvertised object 6047713aff39dc8a9f94952ecf3b136223605eec
    Fetched in submodule path 'modules/gettext/gnulib', but it did not contain 6047713aff39dc8a9f94952ecf3b136223605eec. Direct fetching of that commit failed.
    Failed to recurse into submodule path 'modules/gettext'
submodule checkout attempt 2...
    => error
    error: Server does not allow request for unadvertised object 6047713aff39dc8a9f94952ecf3b136223605eec
    Fetched in submodule path 'modules/gettext/gnulib', but it did not contain 6047713aff39dc8a9f94952ecf3b136223605eec. Direct fetching of that commit failed.
    Failed to recurse into submodule path 'modules/gettext'
submodule checkout attempt 3...
    => error
    error: Server does not allow request for unadvertised object 6047713aff39dc8a9f94952ecf3b136223605eec
    Fetched in submodule path 'modules/gettext/gnulib', but it did not contain 6047713aff39dc8a9f94952ecf3b136223605eec. Direct fetching of that commit failed.
    Failed to recurse into submodule path 'modules/gettext'

from https://results.pre-commit.ci/run/github/116816146/1612858774.myIqOmUUTmGB06u0oFig9w