fix: sanitize variable substitution pattern

replace '${foo+repl}' pattern with '${foo:+repl}' (latest supports $foo being defined but empty)

templates/gitlab-ci-python.yml

@@ -711,20 +711,20 @@ variables:
         then
           log_error "Current version not defined and not version file found, set initial version at least in .bumpversion.toml or pyproject.toml"
         fi
-        bump-my-version bump ${TRACE+--verbose} --current-version "${py_cur_version:-${PYTHON_RELEASE_START_VERSION:-0.0.0}}" --new-version "$py_next_version" --commit ${PYTHON_RELEASE_COMMIT_MESSAGE+--message "$PYTHON_RELEASE_COMMIT_MESSAGE"} --tag --tag-name "{new_version}" "$py_release_part"
+        bump-my-version bump ${TRACE+--verbose} --current-version "${py_cur_version:-${PYTHON_RELEASE_START_VERSION:-0.0.0}}" --new-version "$py_next_version" --commit ${PYTHON_RELEASE_COMMIT_MESSAGE:+--message "$PYTHON_RELEASE_COMMIT_MESSAGE"} --tag --tag-name "{new_version}" "$py_release_part"
       elif [[ -f ".bumpversion.cfg" ]]
       then
         # current version shall be set in .bumpversion.cfg
         py_release_part="$PYTHON_RELEASE_NEXT"
         log_info "[bump-my-version bump] increase \\e[1;94m${py_release_part}\\e[0m"
-        bump-my-version bump ${TRACE+--verbose} --commit ${PYTHON_RELEASE_COMMIT_MESSAGE+--message "$PYTHON_RELEASE_COMMIT_MESSAGE"} --tag --tag-name "{new_version}" "$py_release_part"
+        bump-my-version bump ${TRACE+--verbose} --commit ${PYTHON_RELEASE_COMMIT_MESSAGE:+--message "$PYTHON_RELEASE_COMMIT_MESSAGE"} --tag --tag-name "{new_version}" "$py_release_part"
       elif [[ -f "setup.py" ]]
       then
         # retrieve current version from setup.py
         py_cur_version=$(python setup.py --version)
         py_release_part="$PYTHON_RELEASE_NEXT"
         log_info "[bump-my-version] increase \\e[1;94m${py_release_part}\\e[0m (from current \\e[1;94m${py_cur_version}\\e[0m)"
-        bump-my-version bump ${TRACE+--verbose} --current-version "$py_cur_version" --commit ${PYTHON_RELEASE_COMMIT_MESSAGE+--message "$PYTHON_RELEASE_COMMIT_MESSAGE"} --tag --tag-name "{new_version}" "$py_release_part" setup.py
+        bump-my-version bump ${TRACE+--verbose} --current-version "$py_cur_version" --commit ${PYTHON_RELEASE_COMMIT_MESSAGE:+--message "$PYTHON_RELEASE_COMMIT_MESSAGE"} --tag --tag-name "{new_version}" "$py_release_part" setup.py
       else
         log_error "--- setup.py or .bumpversion.cfg file required to retrieve current version: cannot perform release"
         exit 1