[Merged by Bors] - feat(RingTheory/PowerSeries/WellKnown): the power series of `1 / ((1 - x) ^ (d + 1))` with coefficients in a commutative ring `S`, where `d : ℕ`. #53688

	name: Detect changes to header SHAs

	on:
	pull_request:

	jobs:
	build:
	name: Add annotations
	runs-on: ubuntu-latest
	env:
	GH_TOKEN: ${{ github.token }}
	steps:
	- name: "Checkout mathlib4"
	uses: actions/checkout@v3

	- name: "Checkout mathlib3"
	uses: actions/checkout@v3
	with:
	repository: leanprover-community/mathlib
	path: port-repos/leanprover-community/mathlib

	- name: "Checkout lean3"
	uses: actions/checkout@v3
	with:
	repository: leanprover-community/lean
	path: port-repos/leanprover-community/lean

	- name: Fetch merge base SHA from API
	run: \|
	my_merge_base_cmd="gh api repos/${{ github.repository }}/compare/${{ github.event.pull_request.base.sha }}...${{ github.event.pull_request.head.sha }} \| jq -r '.merge_base_commit.sha'"
	echo $my_merge_base_cmd
	my_merge_base=$(eval $my_merge_base_cmd)
	echo "MY_MERGE_BASE_SHA=$my_merge_base" >> $GITHUB_ENV

	- name: Fetch merge base SHA
	run: \|
	git fetch \
	--no-tags \
	--prune \
	--progress \
	--no-recurse-submodules \
	--depth=1 \
	origin $MY_MERGE_BASE_SHA

	- name: install Python
	uses: actions/setup-python@v4
	with:
	python-version: 3.8

	- name: install script dependencies
	run: \|
	pip install gitpython

	- name: run the script
	run: \|
	python scripts/detect_sha_changes.py "$MY_MERGE_BASE_SHA" "HEAD"

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