diff --git a/hgext3rd/pushvars.py b/hgext3rd/pushvars.py
deleted file mode 100644
--- a/hgext3rd/pushvars.py
+++ /dev/null
@@ -1,17 +0,0 @@
-# pushvars.py -- extension for setting environment variables on the server-side
-#                during pushes.
-#
-# Copyright 2017 Facebook, Inc.
-#
-# This software may be used and distributed according to the terms of the
-# GNU General Public License version 2 or any later version.
-
-def reposetup(ui, repo):
-    """
-    The main pushvars functionality moved into core hg. However, the behavior
-    of the core version differs from this extension, which originally would
-    set the environment variables on the server by default when the extension
-    was enabled. To keep that behavior, this extension now just sets the option.
-    This makes the transition painless.
-    """
-    repo.ui.setconfig('push', 'pushvars.server', True)
diff --git a/hgext3rd/tweakdefaults.py b/hgext3rd/tweakdefaults.py
--- a/hgext3rd/tweakdefaults.py
+++ b/hgext3rd/tweakdefaults.py
@@ -278,6 +278,8 @@
     _fixpager(ui)
     # Allow uncommit on dirty working directory
     repo.ui.setconfig('experimental', 'uncommitondirtywdir', True)
+    # Allow unbundling of pushvars on server
+    repo.ui.setconfig('push', 'pushvars.server', True)
 
 def tweakorder():
     """
diff --git a/tests/test-pushvars-remotenames.t b/tests/test-pushvars-remotenames.t
--- a/tests/test-pushvars-remotenames.t
+++ b/tests/test-pushvars-remotenames.t
@@ -13,7 +13,7 @@
   $ chmod +x $TESTTMP/pretxnchangegroup.sh
   $ cat >> $HGRCPATH << EOF
   > [extensions]
-  > pushvars=$TESTDIR/../hgext3rd/pushvars.py
+  > tweakdefaults=$TESTDIR/../hgext3rd/tweakdefaults.py
   > remotenames=
   > [hooks]
   > pretxnchangegroup = $TESTTMP/pretxnchangegroup.sh
diff --git a/tests/test-pushvars.t b/tests/test-pushvars.t
deleted file mode 100644
--- a/tests/test-pushvars.t
+++ /dev/null
@@ -1,61 +0,0 @@
-Setup
-
-  $ PYTHONPATH=$TESTDIR/..:$PYTHONPATH
-  $ export PYTHONPATH
-
-  $ cat > $TESTTMP/pretxnchangegroup.sh << EOF
-  > #!/bin/sh
-  > env | grep -E "^HG_USERVAR_DEBUG"
-  > env | grep -E "^HG_USERVAR_BYPASS_REVIEW"
-  > exit 0
-  > EOF
-  $ chmod +x $TESTTMP/pretxnchangegroup.sh
-  $ cat >> $HGRCPATH << EOF
-  > [extensions]
-  > pushvars=$TESTDIR/../hgext3rd/pushvars.py
-  > [hooks]
-  > pretxnchangegroup = $TESTTMP/pretxnchangegroup.sh
-  > [experimental]
-  > bundle2-exp = true
-  > EOF
-
-  $ hg init repo
-  $ hg clone -q repo child
-  $ cd child
-
-Test pushing vars to repo
-
-  $ echo b > a
-  $ hg commit -Aqm a
-  $ hg push --pushvars "DEBUG=1" --pushvars "BYPASS_REVIEW=true"
-  pushing to $TESTTMP/repo (glob)
-  searching for changes
-  adding changesets
-  adding manifests
-  adding file changes
-  added 1 changesets with 1 changes to 1 files
-  HG_USERVAR_DEBUG=1
-  HG_USERVAR_BYPASS_REVIEW=true
-
-Test pushing var with empty right-hand side
-
-  $ echo b >> a
-  $ hg commit -Aqm a
-  $ hg push --pushvars "DEBUG="
-  pushing to $TESTTMP/repo (glob)
-  searching for changes
-  adding changesets
-  adding manifests
-  adding file changes
-  added 1 changesets with 1 changes to 1 files
-  HG_USERVAR_DEBUG=
-
-Test pushing bad vars
-
-  $ echo b >> a
-  $ hg commit -Aqm b
-  $ hg push --pushvars "DEBUG"
-  pushing to $TESTTMP/repo (glob)
-  searching for changes
-  abort: unable to parse variable 'DEBUG', should follow 'KEY=VALUE' or 'KEY=' format
-  [255]