update scripts to allow release (copied from smmap)

Makefile

@@ -1,40 +1,12 @@
-PYTHON = python3
-SETUP = $(PYTHON) setup.py
-TESTFLAGS =
+.PHONY: all clean release force_release
 
-all::
+all:
 	@grep -Ee '^[a-z].*:' Makefile | cut -d: -f1 | grep -vF all
 
-release:: clean
-	# Check if latest tag is the current head we're releasing
-	echo "Latest tag = $$(git tag | sort -nr | head -n1)"
-	echo "HEAD SHA       = $$(git rev-parse head)"
-	echo "Latest tag SHA = $$(git tag | sort -nr | head -n1 | xargs git rev-parse)"
-	@test "$$(git rev-parse head)" = "$$(git tag | sort -nr | head -n1 | xargs git rev-parse)"
-	make force_release
+clean:
+	rm -rf build/ dist/ .eggs/ .tox/
 
-force_release:: clean
-	git push --tags
-	python3 -m build --sdist --wheel
+force_release: clean
+	./build-release.sh
 	twine upload dist/*
-
-doc:: 
-	make -C doc/ html
-
-build::
-	$(SETUP) build
-	$(SETUP) build_ext -i
-
-build_ext::
-	$(SETUP) build_ext -i
-
-install::
-	$(SETUP) install
-
-clean::
-	$(SETUP) clean --all
-	rm -f *.so
-
-coverage:: build
-	PYTHONPATH=. $(PYTHON) -m pytest --cov=gitdb gitdb
-
+	git push --tags origin master

build-release.sh

@@ -0,0 +1,26 @@
+#!/bin/bash
+#
+# This script builds a release. If run in a venv, it auto-installs its tools.
+# You may want to run "make release" instead of running this script directly.
+
+set -eEu
+
+function release_with() {
+    $1 -m build --sdist --wheel
+}
+
+if test -n "${VIRTUAL_ENV:-}"; then
+    deps=(build twine)  # Install twine along with build, as we need it later.
+    echo "Virtual environment detected. Adding packages: ${deps[*]}"
+    pip install --quiet --upgrade "${deps[@]}"
+    echo 'Starting the build.'
+    release_with python
+else
+    function suggest_venv() {
+        venv_cmd='python -m venv env && source env/bin/activate'
+        printf "HELP: To avoid this error, use a virtual-env with '%s' instead.\n" "$venv_cmd"
+    }
+    trap suggest_venv ERR  # This keeps the original exit (error) code.
+    echo 'Starting the build.'
+    release_with python3 # Outside a venv, use python3.
+fi