refinements to build-reelase.sh

- use `echo` where feasible to avoid explicit newlines
- use `function` syntax out of habit
- deduplicate release invocation
- make `venv` based invocation less verbose
- make help-text in non-venv more prominent

build-release.sh

@@ -5,18 +5,22 @@
 
 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.
-    printf 'Virtual environment detected. Adding packages: %s\n' "${deps[*]}"
-    pip install -U "${deps[@]}"
-    printf 'Starting the build.\n'
-    python -m build --sdist --wheel
+    echo "Virtual environment detected. Adding packages: ${deps[*]}"
+    pip install --quiet --upgrade "${deps[@]}"
+    echo 'Starting the build.'
+    release_with python
 else
-    suggest_venv() {
+    function suggest_venv() {
         venv_cmd='python -m venv env && source env/bin/activate'
-        printf "Use a virtual-env with '%s' instead.\n" "$venv_cmd"
+        printf "HELP: To avoid this error, use a virtual-env with '%s' instead.\n" "$venv_cmd"
     }
     trap suggest_venv ERR  # This keeps the original exit (error) code.
-    printf 'Starting the build.\n'
-    python3 -m build --sdist --wheel  # Outside a venv, use python3.
+    echo 'Starting the build.'
+    release_with python3 # Outside a venv, use python3.
 fi