(a) Well, if you the author think there’s no need to keep it, I’m convinced. (I was pretty close to convinced already. :- )

(b) Way ahead of you, mate. Plan is to make the file potentially more useful, have it use the TEI namespace (because the code that interrogates it already has xpath-default-namespace=TEI), and call it repo_info.xml, instead. E.g., here is my current local version:

<?xml version="1.0" encoding="UTF-8"?>
<application xmlns="http://www.tei-c.org/ns/1.0" ident="git" version="2.25.1" when="2021-02-12T16:27:46-05:00" n="381fd17f6">
  <ab type="status">
On branch sydb-improve_expand
Changes not staged for commit:
  (use "git add &lt;file&gt;..." to update what will be committed)
  (use "git restore &lt;file&gt;..." to discard changes in working directory)
modified:   Makefile

no changes added to commit (use "git add" and/or "git commit -a")
</ab>
</application>

This means that the expansion code could just use /application/@n for the commit #, for example. (What it does now is somwhat more convoluted.)

I am not at all sure why the leading space in front of “</ab>” is missing, but I also don’t think it is worth much of my time to figure out.
 
I did a bit of spelunking because I thought I remembered writing that code, and indeed, https://github.com/TEIC/TEI/commit/0e10f2baa211cf86e9a898389bc26c2df92ea9fb, way back in 2014! I was just starting the project of convincing Council to move to Git from Subversion :-).

I think a) there's no need to keep the svn code, and b) we might think about cleaner ways to do it, because it intentionally makes git imitate the svn info XML format (so that it wouldn't make a difference which version control system you used).