The "runs_on_pool" environment variable is used by our CI scripts to
distinguish the different kinds of operating systems. It is quite
specific to GitHub Actions though and not really a descriptive name.
Rename the variable to "distro" to clarify its intent.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2d65e5b6a6