merge(third_party/git): Merge squashed git subtree at v2.23.0

Merge commit '1b593e1ea4' as 'third_party/git'

third_party/git/contrib/coccinelle/commit.cocci

@@ -0,0 +1,34 @@
+@@
+expression c;
+@@
+- &c->maybe_tree->object.oid
++ get_commit_tree_oid(c)
+
+@@
+expression c;
+@@
+- c->maybe_tree->object.oid.hash
++ get_commit_tree_oid(c)->hash
+
+@@
+identifier f !~ "^set_commit_tree$";
+expression c;
+expression s;
+@@
+  f(...) {<...
+- c->maybe_tree = s
++ set_commit_tree(c, s)
+  ...>}
+
+// These excluded functions must access c->maybe_tree direcly.
+// Note that if c->maybe_tree is written somewhere outside of these
+// functions, then the recommended transformation will be bogus with
+// repo_get_commit_tree() on the LHS.
+@@
+identifier f !~ "^(repo_get_commit_tree|get_commit_tree_in_graph_one|load_tree_for_commit|set_commit_tree)$";
+expression c;
+@@
+  f(...) {<...
+- c->maybe_tree
++ repo_get_commit_tree(specify_the_right_repo_here, c)
+  ...>}