Ævar Arnfjörð Bjarmason  [off-list ref] writes:

From: Emily Shaffer <redacted>

Expose the "path_to_stdin" API added in the preceding commit in the
"git hook run" command.

For now we won't be using this command interface outside of the tests,
but exposing this functionality makes it easier to test the hook
API. The plan is to use this to extend the "sendemail-validate"
hook[1][2].

OK.

What does it take to tackle the obvious leftover bits of [4/5]?  Use
tempfile API to allocate a temporary file, slurp the input and close
it, and then use the "path_to_stdin" feature to spawn the hook?