diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -6142,8 +6142,20 @@ def unbundle(ui, repo, fname1, *fnames, 
         for fname in fnames:
             f = hg.openpath(ui, fname)
             gen = exchange.readbundle(ui, f, fname)
-            modheads = changegroup.addchangegroup(repo, gen, 'unbundle',
-                                                  'bundle:' + fname)
+            if isinstance(gen, bundle2.unbundle20):
+                tr = repo.transaction('unbundle')
+                try:
+                    op = bundle2.processbundle(repo, gen, lambda: tr)
+                    tr.close()
+                finally:
+                    if tr:
+                        tr.release()
+                changes = [r.get('result', 0)
+                           for r in op.records['changegroup']]
+                modheads = changegroup.combineresults(changes)
+            else:
+                modheads = changegroup.addchangegroup(repo, gen, 'unbundle',
+                                                      'bundle:' + fname)
     finally:
         lock.release()
 
diff --git a/tests/test-bundle2-format.t b/tests/test-bundle2-format.t
--- a/tests/test-bundle2-format.t
+++ b/tests/test-bundle2-format.t
@@ -762,13 +762,11 @@ Support for changegroup
       9520eea781bcca16c1e15acc0ba14335a0e8e5ba
       eea13746799a9e0bfd88f29d3c2e9dc9389f524f
       02de42196ebee42ef284b6780a87cdc96e8eaab6
-  $ hg unbundle2 < ../rev.hg2
+  $ hg unbundle ../rev.hg2
   adding changesets
   adding manifests
   adding file changes
   added 0 changesets with 0 changes to 3 files
-  0 unread bytes
-  addchangegroup return: 1
 
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