vimPlugins: Ignore empty commits in update.py
vimPlugins: Ignore empty commits in update.py

The result of repo.index.add() contains the list of files that
have been added, even though they may be unchanged since the
latest commit. We only commit if at least one file has changed.

NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs