diff --git a/mercurial/httppeer.py b/mercurial/httppeer.py
--- a/mercurial/httppeer.py
+++ b/mercurial/httppeer.py
@@ -754,7 +754,8 @@ class httpv2executor(object):
                         try:
                             result.append(decoder.decode())
                         except Exception:
-                            f.set_exception_info(*sys.exc_info()[1:])
+                            pycompat.future_set_exception_info(
+                                f, sys.exc_info()[1:])
                             continue
                 else:
                     result.append(meta['data'])
diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py
--- a/mercurial/localrepo.py
+++ b/mercurial/localrepo.py
@@ -184,7 +184,7 @@ class localcommandexecutor(object):
         try:
             result = fn(**args)
         except Exception:
-            f.set_exception_info(*sys.exc_info()[1:])
+            pycompat.future_set_exception_info(f, sys.exc_info()[1:])
         else:
             f.set_result(result)
 
diff --git a/mercurial/pycompat.py b/mercurial/pycompat.py
--- a/mercurial/pycompat.py
+++ b/mercurial/pycompat.py
@@ -28,6 +28,9 @@ if not ispy3:
     import xmlrpclib
 
     from .thirdparty.concurrent import futures
+
+    def future_set_exception_info(f, exc_info):
+        f.set_exception_info(*exc_info)
 else:
     import concurrent.futures as futures
     import http.cookiejar as cookielib
@@ -37,6 +40,9 @@ else:
     import socketserver
     import xmlrpc.client as xmlrpclib
 
+    def future_set_exception_info(f, exc_info):
+        f.set_exception(exc_info[0])
+
 empty = _queue.Empty
 queue = _queue.Queue
 
diff --git a/mercurial/wireprotov1peer.py b/mercurial/wireprotov1peer.py
--- a/mercurial/wireprotov1peer.py
+++ b/mercurial/wireprotov1peer.py
@@ -209,7 +209,7 @@ class peerexecutor(object):
             try:
                 result = fn(**pycompat.strkwargs(args))
             except Exception:
-                f.set_exception_info(*sys.exc_info()[1:])
+                pycompat.future_set_exception_info(f, sys.exc_info()[1:])
             else:
                 f.set_result(result)
 
@@ -234,14 +234,14 @@ class peerexecutor(object):
                 batchable = fn.batchable(fn.__self__,
                                          **pycompat.strkwargs(args))
             except Exception:
-                f.set_exception_info(*sys.exc_info()[1:])
+                pycompat.future_set_exception_info(f, sys.exc_info()[1:])
                 return
 
             # Encoded arguments and future holding remote result.
             try:
                 encodedargs, fremote = next(batchable)
             except Exception:
-                f.set_exception_info(*sys.exc_info()[1:])
+                pycompat.future_set_exception_info(f, sys.exc_info()[1:])
                 return
 
             requests.append((command, encodedargs))
@@ -304,7 +304,7 @@ class peerexecutor(object):
             try:
                 result = next(batchable)
             except Exception:
-                f.set_exception_info(*sys.exc_info()[1:])
+                pycompat.future_set_exception_info(f, sys.exc_info()[1:])
             else:
                 f.set_result(result)