message: also pass flags to install
diff: @@ -103,7 +103,7 @@ case "$COMMAND" in
  install|install-debug)
  # "--locked" to respect the Cargo.lock file if it exists,
  # "--offline" to avoid querying the registry (for yanked packages).
  - exec cargo install --path "$(dirname "$0")" --force --locked --offline "$@"
  + exec cargo install $CARGO_INSTALL_FLAGS --path "$(dirname "$0")" --force --locked --offline "$@"
  ;;
  build|build-debug)
  # Build, and let caller control flags.
  