fix: the generated build epoch belongs to the generated wheel, and thus both files should be generated using the same recipe (#1126)

Refs: 260075b

Author: jenstroeger

Makefile

@@ -182,21 +182,17 @@ test-all: test-unit test-integration test-performance
 # When building these artifacts, we need the environment variable SOURCE_DATE_EPOCH
 # set to the build date/epoch. For more details, see: https://flit.pypa.io/en/latest/reproducible.html
 .PHONY: dist
-dist: dist/$(PACKAGE_NAME)-$(PACKAGE_VERSION)-py3-none-any.whl dist/$(PACKAGE_NAME)-$(PACKAGE_VERSION).tar.gz dist/$(PACKAGE_NAME)-$(PACKAGE_VERSION)-docs-html.zip dist/$(PACKAGE_NAME)-$(PACKAGE_VERSION)-docs-md.zip dist/$(PACKAGE_NAME)-$(PACKAGE_VERSION)-build-epoch.txt
-dist/$(PACKAGE_NAME)-$(PACKAGE_VERSION)-py3-none-any.whl: check test-all dist/$(PACKAGE_NAME)-$(PACKAGE_VERSION)-build-epoch.txt
+dist: dist/$(PACKAGE_NAME)-$(PACKAGE_VERSION)-py3-none-any.whl dist/$(PACKAGE_NAME)-$(PACKAGE_VERSION).tar.gz dist/$(PACKAGE_NAME)-$(PACKAGE_VERSION)-docs-html.zip dist/$(PACKAGE_NAME)-$(PACKAGE_VERSION)-docs-md.zip
+dist/$(PACKAGE_NAME)-$(PACKAGE_VERSION)-py3-none-any.whl: check test-all
 	SOURCE_DATE_EPOCH=$(SOURCE_DATE_EPOCH) python -m flit build --setup-py --format wheel
-dist/$(PACKAGE_NAME)-$(PACKAGE_VERSION).tar.gz: check test-all dist/$(PACKAGE_NAME)-$(PACKAGE_VERSION)-build-epoch.txt
+	echo $(SOURCE_DATE_EPOCH) > dist/$(PACKAGE_NAME)-$(PACKAGE_VERSION)-py3-none-any-build-epoch.txt
+dist/$(PACKAGE_NAME)-$(PACKAGE_VERSION).tar.gz: check test-all
 	SOURCE_DATE_EPOCH=$(SOURCE_DATE_EPOCH) python -m flit build --no-setup-py --format sdist
 dist/$(PACKAGE_NAME)-$(PACKAGE_VERSION)-docs-html.zip: docs-html
 	python -m zipfile -c dist/$(PACKAGE_NAME)-$(PACKAGE_VERSION)-docs-html.zip docs/_build/html/
 dist/$(PACKAGE_NAME)-$(PACKAGE_VERSION)-docs-md.zip: docs-md
 	python -m zipfile -c dist/$(PACKAGE_NAME)-$(PACKAGE_VERSION)-docs-md.zip docs/_build/markdown/
 
-# Keep this goal phony to ensure the epoch is always updated.
-.PHONY: dist/$(PACKAGE_NAME)-$(PACKAGE_VERSION)-build-epoch.txt
-dist/$(PACKAGE_NAME)-$(PACKAGE_VERSION)-build-epoch.txt:
-	echo $(SOURCE_DATE_EPOCH) > dist/$(PACKAGE_NAME)-$(PACKAGE_VERSION)-build-epoch.txt
-
 # Build a PEP-503 compatible Simple Repository directory inside of dist/. For details on
 # the layout of that directory and the normalized project name, see: https://peps.python.org/pep-0503/
 # The directory can then be used to install (hashed) artifacts by using `pip` and