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+# Contributing to this fork
+
+This repository is a fork. Its integration branch is `master`: it carries every
+change made in this fork, and it is the only branch that projects depending on
+the fork should consume (a dependent can follow just one branch).
+
+- **Changes land here first.** Every fix or feature goes to `master` through a pull
+  request merged with a merge commit. Branches that dependents pin are never
+  rebased or force-pushed.
+- **Upstream proposals are cut separately.** Once a change is on `master`, the
+  pull request for the upstream project is cut fresh from upstream's default
+  branch as a single-purpose change (one concern, one commit, following
+  upstream's conventions). It is not merged from `master`.
+- **Upstream is merged in regularly.** Upstream's default branch is merged into
+  `master` so the fork stays a superset of upstream.
+- **Before an upstream pull request merges or closes,** check that its content is
+  on `master` (by content, not commit hashes: upstream branches are re-cut).