Stop rewriting message to include PR URL

defs/gmake.mk

@@ -201,9 +201,6 @@ define pull-github
 	$(eval GITHUB_MERGE_WORKTREE := $(shell mktemp -d "$(srcdir)/gh-$(1)-XXXXXX"))
 	git -C "$(srcdir)" worktree add $(notdir $(GITHUB_MERGE_WORKTREE)) "gh-$(1)"
 	git -C "$(GITHUB_MERGE_WORKTREE)" rebase $(GITHUB_MERGE_BRANCH)
-	git -C "$(GITHUB_MERGE_WORKTREE)" filter-branch -f \
-	  --msg-filter 'cat && echo && echo "Closes: $(GITHUB_RUBY_URL)/pull/$(1)"' \
-	  -- "$(GITHUB_MERGE_BASE)..@"
 	$(eval COMMIT_GPG_SIGN := $(COMMIT_GPG_SIGN))
 	$(if $(filter true,$(COMMIT_GPG_SIGN)), \
 	  git -C "$(GITHUB_MERGE_WORKTREE)" rebase --exec "git commit --amend --no-edit -S" "$(GITHUB_MERGE_BASE)"; \