The test/migrations jobs check out fetch-depth:1. A shallow clone has NO
origin/<base> tracking ref and no merge-base, so the three-dot
origin/main...HEAD errored -> empty diff -> docs_only=false -> EVERY docs-only PR
silently ran the full matrix (safe but the skip never fired). git fetch always
writes FETCH_HEAD, which resolves in a shallow clone; diff against it with a
two-dot tree diff (no merge-base). Confirmed in a real shallow file:// clone:
origin/main did NOT resolve and three-dot errored, while FETCH_HEAD two-dot
correctly returned the docs file. api-docs/format were unaffected only because
they use fetch-depth:0.
Refs #416
The changed-set git diff had rename detection on by default, so a code->docs
rename (Foo.cs -> docs/Foo.md) showed only the destination and was misclassified
as docs-only, skipping required tests on a code change. --no-renames surfaces the
source deletion -> full matrix. Empirically verified. This is the cold-review
MEDIUM; it was applied in the working tree but never committed before the first
push (index/worktree mismatch) — committing it now.
Refs #416
Docs-only changes (docs/** or *.md) ran the full docker-build matrix (~9 min).
Each heavy job (test, migrations, functional-e2e, build) now runs
scripts/ci-detect-docs-only.sh as its first post-checkout step and gates every
real step on docs_only!='true'. The jobs still RUN and report success in
seconds, so the two required contexts keep reporting — a docs-only PR stays
mergeable (never an if:-skipped required job; Gitea 1.25.4 reports if-skip as
'skipped', verified with a throwaway probe PR). build skips its image steps on a
docs-only push to main; tag builds force docs_only=false. Detection uses
--no-renames so a code->docs rename can never be misclassified as docs-only.
Refs #416