commit: use `dirstate.change_files` to scope the associated `addremove` This was significantly more complicated than I expected, because multiple extensions get in the way. I introduced a context that lazily open the transaction and associated context to work around these complication. See the inline documentation for details. Introducing the wrapping transaction remove the need for dirstate-guard (one of the ultimate goal of all this), and slightly affect the result of a `hg rollback` after a `hg commit --addremove`. That last part is deemed fine. It aligns the behavior with what happens after a failed `hg commit --addremove` and nobody should be using `hg rollback` anyway. The small output change in the test come from the different transaction timing and fact the transaction now backup the dirstate before the addremove, which might mean "no file to backup" when the repository starts from an empty state.

--- a/mercurial/scmutil.py	Sun Feb 05 15:38:23 2023 +0100
+++ b/mercurial/scmutil.py	Wed Feb 15 11:51:58 2023 +0100
@@ -1219,7 +1219,7 @@
                 )
 
 
-def addremove(repo, matcher, prefix, uipathfn, opts=None):
+def addremove(repo, matcher, prefix, uipathfn, opts=None, open_tr=None):
     if opts is None:
         opts = {}
     m = matcher
@@ -1279,7 +1279,9 @@
         repo, m, added + unknown, removed + deleted, similarity, uipathfn
     )
 
-    if not dry_run:
+    if not dry_run and (unknown or forgotten or deleted or renames):
+        if open_tr is not None:
+            open_tr()
         _markchanges(repo, unknown + forgotten, deleted, renames)
 
     for f in rejected: