Alpine splits git-http-backend OUT of the `git` package: git alone ships
git-remote-http/https but not the CGI backend. The runner therefore had git
2.52.0 and no git-http-backend, so zegit's internal/forgeprobe smart-HTTP tests
failed at request time with "fork/exec git-http-backend: no such file or
directory" and reported three FAILURES for a missing tool.
That turned Gitea CI red on every zegit master commit while GitHub stayed
green, for hours, with nobody looking — GitHub is the release oracle, which is
exactly why a red mirror is invisible.
Verified against the real base image, not just alpine:3 — on
code.forgejo.org/forgejo/runner:12.11.1 (Alpine 3.23), `apk add git git-daemon`
puts git-http-backend at /usr/libexec/git-core/git-http-backend, and
`git --exec-path` resolves to that directory, which is the lookup the test
harness performs.
