Forcing rewrite of files in working tree

Hello,

I want to write a little recipe in a Makefile that ensures the $Id$ field in a series of text files is correct. In case it's relevant, I'm including a load of asciidoc files as subsections into one master file; each file has a $Id$ field in the header, which very nicely prints out at the start of each section. However, the $Id$ field is only written on checkout (not on checkin for fairly obvious reasons). That means that for any files I've changed, the $Id$ is wrong. Before I generate output using ASCIIdoc I'd like to ensure the $Id$ is correct.

How do I do it?

The only method I've found is to delete the file in the work tree then do git-checkout again. Even with -f, if the file is not changed git doesn't perform a checkout again, so git-checkout -f is not sufficient. I assume I can do what I want with some clever plumbing, but I don't know any plumbing. :-)

Andy