--- a/mercurial/metadata.py	Sat Jul 25 15:55:09 2020 +0200
+++ b/mercurial/metadata.py	Sat Jul 25 16:02:26 2020 +0200
@@ -254,6 +254,30 @@
         return None
 
 
+def encode_copies_sidedata(files):
+    sortedfiles = sorted(files.touched)
+    sidedata = {}
+    p1copies = files.copied_from_p1
+    if p1copies:
+        p1copies = encodecopies(sortedfiles, p1copies)
+        sidedata[sidedatamod.SD_P1COPIES] = p1copies
+    p2copies = files.copied_from_p2
+    if p2copies:
+        p2copies = encodecopies(sortedfiles, p2copies)
+        sidedata[sidedatamod.SD_P2COPIES] = p2copies
+    filesadded = files.added
+    if filesadded:
+        filesadded = encodefileindices(sortedfiles, filesadded)
+        sidedata[sidedatamod.SD_FILESADDED] = filesadded
+    filesremoved = files.removed
+    if filesremoved:
+        filesremoved = encodefileindices(sortedfiles, filesremoved)
+        sidedata[sidedatamod.SD_FILESREMOVED] = filesremoved
+    if not sidedata:
+        sidedata = None
+    return sidedata
+
+
 def _getsidedata(srcrepo, rev):
     ctx = srcrepo[rev]
     filescopies = computechangesetcopies(ctx)