tools: Add git utility scripts.

tools/clean-repo

@@ -0,0 +1,13 @@
+#!/usr/bin/env bash
+set -e
+
+# Remove .pyc files to prevent loading stale code.
+#
+# You can run it automatically on checkout:
+#
+#     echo ./tools/clean-repo > .git/hooks/post-checkout
+#     chmod +x .git/hooks/post-checkout
+
+cd "$(dirname "$0")/.."
+find . -name "*.pyc" -exec rm -f {} \;
+find . -name "__pycache__" -prune -exec rm -rf {} \;