diff --git a/mercurial/bundle2.py b/mercurial/bundle2.py
--- a/mercurial/bundle2.py
+++ b/mercurial/bundle2.py
@@ -268,12 +268,13 @@ class bundleoperation(object):
     * a way to construct a bundle response when applicable.
     """
 
-    def __init__(self, repo, transactiongetter):
+    def __init__(self, repo, transactiongetter, captureoutput=True):
         self.repo = repo
         self.ui = repo.ui
         self.records = unbundlerecords()
         self.gettransaction = transactiongetter
         self.reply = None
+        self.captureoutput = captureoutput
 
 class TransactionUnavailable(RuntimeError):
     pass
@@ -359,7 +360,7 @@ def _processpart(op, part):
         # parthandlermapping lookup (any KeyError raised by handler()
         # itself represents a defect of a different variety).
         output = None
-        if op.reply is not None:
+        if op.captureoutput and op.reply is not None:
             op.ui.pushbuffer(error=True, subproc=True)
             output = ''
         try:
@@ -840,6 +841,7 @@ class interruptoperation(object):
     def __init__(self, ui):
         self.ui = ui
         self.reply = None
+        self.captureoutput = False
 
     @property
     def repo(self):
diff --git a/mercurial/exchange.py b/mercurial/exchange.py
--- a/mercurial/exchange.py
+++ b/mercurial/exchange.py
@@ -1285,6 +1285,11 @@ def unbundle(repo, cg, heads, source, ur
     # need a transaction when processing a bundle2 stream
     wlock = lock = tr = None
     recordout = None
+    # quick fix for output mismatch with bundle2 in 3.4
+    captureoutput = repo.ui.configbool('experimental', 'bundle2-output-capture',
+                                       False)
+    if url.startswith('remote:http:') or url.startswith('remote:https:'):
+        captureoutput = True
     try:
         check_heads(repo, heads, 'uploading changes')
         # push can proceed
@@ -1297,19 +1302,20 @@ def unbundle(repo, cg, heads, source, ur
                 tr.hookargs['source'] = source
                 tr.hookargs['url'] = url
                 tr.hookargs['bundle2'] = '1'
-                op = bundle2.bundleoperation(repo, lambda: tr)
+                op = bundle2.bundleoperation(repo, lambda: tr,
+                                             captureoutput=captureoutput)
                 try:
                     r = bundle2.processbundle(repo, cg, op=op)
                 finally:
                     r = op.reply
-                    if r is not None:
+                    if captureoutput and r is not None:
                         repo.ui.pushbuffer(error=True, subproc=True)
                         def recordout(output):
                             r.newpart('output', data=output, mandatory=False)
                 tr.close()
             except Exception, exc:
                 exc.duringunbundle2 = True
-                if r is not None:
+                if captureoutput and r is not None:
                     parts = exc._bundle2salvagedoutput = r.salvageoutput()
                     def recordout(output):
                         part = bundle2.bundlepart('output', data=output,
diff --git a/tests/test-bundle2-exchange.t b/tests/test-bundle2-exchange.t
--- a/tests/test-bundle2-exchange.t
+++ b/tests/test-bundle2-exchange.t
@@ -16,6 +16,7 @@ enable obsolescence
   > [experimental]
   > evolution=createmarkers,exchange
   > bundle2-exp=True
+  > bundle2-output-capture=True
   > [ui]
   > ssh=python "$TESTDIR/dummyssh"
   > logtemplate={rev}:{node|short} {phase} {author} {bookmarks} {desc|firstline}
@@ -667,3 +668,52 @@ Check error from hook during the unbundl
   remote: rollback completed
   abort: pretxnchangegroup hook exited with status 1
   [255]
+
+Check output capture control.
+
+(should be still forced for http, disabled for local and ssh)
+
+  $ cat >> $HGRCPATH << EOF
+  > [experimental]
+  > bundle2-output-capture=False
+  > EOF
+
+  $ hg -R main push other -r e7ec4e813ba6
+  pushing to other
+  searching for changes
+  adding changesets
+  adding manifests
+  adding file changes
+  added 1 changesets with 1 changes to 1 files
+  Fail early!
+  transaction abort!
+  Cleaning up the mess...
+  rollback completed
+  abort: pretxnchangegroup hook exited with status 1
+  [255]
+  $ hg -R main push ssh://user@dummy/other -r e7ec4e813ba6
+  pushing to ssh://user@dummy/other
+  searching for changes
+  abort: pretxnchangegroup hook exited with status 1
+  remote: adding changesets
+  remote: adding manifests
+  remote: adding file changes
+  remote: added 1 changesets with 1 changes to 1 files
+  remote: Fail early!
+  remote: transaction abort!
+  remote: Cleaning up the mess...
+  remote: rollback completed
+  [255]
+  $ hg -R main push http://localhost:$HGPORT2/ -r e7ec4e813ba6
+  pushing to http://localhost:$HGPORT2/
+  searching for changes
+  remote: adding changesets
+  remote: adding manifests
+  remote: adding file changes
+  remote: added 1 changesets with 1 changes to 1 files
+  remote: Fail early!
+  remote: transaction abort!
+  remote: Cleaning up the mess...
+  remote: rollback completed
+  abort: pretxnchangegroup hook exited with status 1
+  [255]