Every changed-path gate asked git for `--merge-base "$BASE_SHA" "$HEAD_SHA"`,
which needs the event payload's base SHA to be in the local graph. That is the
only reason two jobs cloned all 8127 refs' history. On a pull_request checkout
HEAD is already the merge commit, so its first parent is the base side and no
merge base has to be computed. config/scripts/git-pull-request-diff-base.mjs
resolved that for the two Node gates; the workflow's inline gates now use the
same helper through a small CLI rather than open-coding it.
code_paths gates all 22 jobs, so its checkout is charged to the start of every
one of them: measured 20.7s to 1.6s, keeping blob:none because its sparse tree
is ~7 files and leaves no blobs to refetch. Static analysis drops the filter
instead, since populating all 30,226 files makes blob:none force a second
promisor fetch: 23s to ~11s.
Verified on a real merge ref. At depth 50 the old and new forms produce
identical changed-file sets. At depth 2 the new form still works and the old one
fails with `fatal: bad object`, which is the failure a stale base would have
caused once the checkout stopped being complete.
Also drops the dead resolveBase + merge-base prelude in the changed-code gate,
whose result resolvePullRequestDiffBase already discarded on every PR.
Neil
080c562898