diff --git a/mercurial/changelog.py b/mercurial/changelog.py
--- a/mercurial/changelog.py
+++ b/mercurial/changelog.py
@@ -561,43 +561,21 @@ class changelog(revlog.revlog):
                 )
         sortedfiles = sorted(files)
         sidedata = None
-        if extra is not None:
-            for name in (
-                b'p1copies',
-                b'p2copies',
-                b'filesadded',
-                b'filesremoved',
-            ):
-                extra.pop(name, None)
-        if p1copies is not None:
-            p1copies = metadata.encodecopies(sortedfiles, p1copies)
-        if p2copies is not None:
-            p2copies = metadata.encodecopies(sortedfiles, p2copies)
-        if filesadded is not None:
-            filesadded = metadata.encodefileindices(sortedfiles, filesadded)
-        if filesremoved is not None:
-            filesremoved = metadata.encodefileindices(sortedfiles, filesremoved)
-        if self._copiesstorage == b'extra':
-            extrasentries = p1copies, p2copies, filesadded, filesremoved
-            if extra is None and any(x is not None for x in extrasentries):
-                extra = {}
-            if p1copies is not None:
-                extra[b'p1copies'] = p1copies
-            if p2copies is not None:
-                extra[b'p2copies'] = p2copies
-            if filesadded is not None:
-                extra[b'filesadded'] = filesadded
-            if filesremoved is not None:
-                extra[b'filesremoved'] = filesremoved
-        elif self._copiesstorage == b'changeset-sidedata':
+        if self._copiesstorage == b'changeset-sidedata':
             sidedata = {}
             if p1copies:
+                p1copies = metadata.encodecopies(sortedfiles, p1copies)
                 sidedata[sidedatamod.SD_P1COPIES] = p1copies
             if p2copies:
+                p2copies = metadata.encodecopies(sortedfiles, p2copies)
                 sidedata[sidedatamod.SD_P2COPIES] = p2copies
             if filesadded:
+                filesadded = metadata.encodefileindices(sortedfiles, filesadded)
                 sidedata[sidedatamod.SD_FILESADDED] = filesadded
             if filesremoved:
+                filesremoved = metadata.encodefileindices(
+                    sortedfiles, filesremoved
+                )
                 sidedata[sidedatamod.SD_FILESREMOVED] = filesremoved
             if not sidedata:
                 sidedata = None
diff --git a/mercurial/commit.py b/mercurial/commit.py
--- a/mercurial/commit.py
+++ b/mercurial/commit.py
@@ -69,6 +69,20 @@ def commitctx(repo, ctx, error=False, or
 
         extra = ctx.extra().copy()
 
+        files = sorted(files)
+        if extra is not None:
+            for name in (
+                b'p1copies',
+                b'p2copies',
+                b'filesadded',
+                b'filesremoved',
+            ):
+                extra.pop(name, None)
+        if repo.changelog._copiesstorage == b'extra':
+            extra = _extra_with_copies(
+                repo, extra, files, p1copies, p2copies, filesadded, filesremoved
+            )
+
         # update changelog
         repo.ui.note(_(b"committing changelog\n"))
         repo.changelog.delayupdate(tr)
@@ -407,3 +421,25 @@ def _commit_manifest(tr, linkrev, ctx, m
         mn = p1.manifestnode()
 
     return mn
+
+
+def _extra_with_copies(
+    repo, extra, files, p1copies, p2copies, filesadded, filesremoved
+):
+    """encode copy information into a `extra` dictionnary"""
+    extrasentries = p1copies, p2copies, filesadded, filesremoved
+    if extra is None and any(x is not None for x in extrasentries):
+        extra = {}
+    if p1copies is not None:
+        p1copies = metadata.encodecopies(files, p1copies)
+        extra[b'p1copies'] = p1copies
+    if p2copies is not None:
+        p2copies = metadata.encodecopies(files, p2copies)
+        extra[b'p2copies'] = p2copies
+    if filesadded is not None:
+        filesadded = metadata.encodefileindices(files, filesadded)
+        extra[b'filesadded'] = filesadded
+    if filesremoved is not None:
+        filesremoved = metadata.encodefileindices(files, filesremoved)
+        extra[b'filesremoved'] = filesremoved
+    return extra