Hello Reuben,
* Reuben Thomas wrote on Thu, Nov 18, 2010 at 09:36:44PM CET:
> The simplest thing seems to be to set the "ident" attribute on all the .m4
> files, and change the line:
>
> #serial nn
>
> to
>
> #$Id$
>
> which then gets expanded to the commit (i.e. blob) ID of the last commit in
> each case.
>
> They're not monotonically increasing, but that doesn't seem to be important;
> they are (pretty much guaranteed to be) unique in the history of any one
> file.
The serial number needs to be a simple number. And aclocal does
consider higher numbers as newer than lower ones.
After much study, it seems that what is needed is a git pre-commit hook which runs ./set-serial.sh on the output of git diff --cached --name-only (possibly filtered by "\.m4$"). Does this sound reasonable?