diff --git a/contrib/synthrepo.py b/contrib/synthrepo.py
--- a/contrib/synthrepo.py
+++ b/contrib/synthrepo.py
@@ -41,6 +41,10 @@ from mercurial import cmdutil, context, 
 from mercurial.i18n import _
 from mercurial.node import nullrev, nullid, short
 
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 cmdtable = {}
diff --git a/hgext/acl.py b/hgext/acl.py
--- a/hgext/acl.py
+++ b/hgext/acl.py
@@ -195,6 +195,10 @@ from mercurial.i18n import _
 from mercurial import util, match
 import getpass, urllib
 
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 def _getusers(ui, group):
diff --git a/hgext/blackbox.py b/hgext/blackbox.py
--- a/hgext/blackbox.py
+++ b/hgext/blackbox.py
@@ -35,6 +35,10 @@ import errno, os, re
 
 cmdtable = {}
 command = cmdutil.command(cmdtable)
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 lastblackbox = None
 
diff --git a/hgext/bugzilla.py b/hgext/bugzilla.py
--- a/hgext/bugzilla.py
+++ b/hgext/bugzilla.py
@@ -282,6 +282,10 @@ from mercurial.node import short
 from mercurial import cmdutil, mail, util
 import re, time, urlparse, xmlrpclib
 
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 class bzaccess(object):
diff --git a/hgext/censor.py b/hgext/censor.py
--- a/hgext/censor.py
+++ b/hgext/censor.py
@@ -31,6 +31,10 @@ from mercurial.i18n import _
 
 cmdtable = {}
 command = cmdutil.command(cmdtable)
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 @command('censor',
diff --git a/hgext/children.py b/hgext/children.py
--- a/hgext/children.py
+++ b/hgext/children.py
@@ -20,6 +20,10 @@ from mercurial.i18n import _
 
 cmdtable = {}
 command = cmdutil.command(cmdtable)
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 @command('children',
diff --git a/hgext/churn.py b/hgext/churn.py
--- a/hgext/churn.py
+++ b/hgext/churn.py
@@ -16,6 +16,10 @@ import time, datetime
 
 cmdtable = {}
 command = cmdutil.command(cmdtable)
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 def maketemplater(ui, repo, tmpl):
diff --git a/hgext/color.py b/hgext/color.py
--- a/hgext/color.py
+++ b/hgext/color.py
@@ -162,6 +162,10 @@ from mercurial.i18n import _
 
 cmdtable = {}
 command = cmdutil.command(cmdtable)
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 # start and stop parameters for effects
diff --git a/hgext/convert/__init__.py b/hgext/convert/__init__.py
--- a/hgext/convert/__init__.py
+++ b/hgext/convert/__init__.py
@@ -15,6 +15,10 @@ from mercurial.i18n import _
 
 cmdtable = {}
 command = cmdutil.command(cmdtable)
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 # Commands definition was moved elsewhere to ease demandload job.
diff --git a/hgext/eol.py b/hgext/eol.py
--- a/hgext/eol.py
+++ b/hgext/eol.py
@@ -95,6 +95,10 @@ from mercurial.i18n import _
 from mercurial import util, config, extensions, match, error
 import re, os
 
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 # Matches a lone LF, i.e., one that is not part of CRLF.
diff --git a/hgext/extdiff.py b/hgext/extdiff.py
--- a/hgext/extdiff.py
+++ b/hgext/extdiff.py
@@ -67,6 +67,10 @@ import os, shlex, shutil, tempfile, re
 
 cmdtable = {}
 command = cmdutil.command(cmdtable)
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 def snapshot(ui, repo, files, node, tmproot):
diff --git a/hgext/fetch.py b/hgext/fetch.py
--- a/hgext/fetch.py
+++ b/hgext/fetch.py
@@ -15,6 +15,10 @@ from mercurial import exchange
 
 cmdtable = {}
 command = cmdutil.command(cmdtable)
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 @command('fetch',
diff --git a/hgext/gpg.py b/hgext/gpg.py
--- a/hgext/gpg.py
+++ b/hgext/gpg.py
@@ -12,6 +12,10 @@ from mercurial.i18n import _
 
 cmdtable = {}
 command = cmdutil.command(cmdtable)
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 class gpg(object):
diff --git a/hgext/graphlog.py b/hgext/graphlog.py
--- a/hgext/graphlog.py
+++ b/hgext/graphlog.py
@@ -20,6 +20,10 @@ from mercurial import cmdutil, commands
 
 cmdtable = {}
 command = cmdutil.command(cmdtable)
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 @command('glog',
diff --git a/hgext/hgcia.py b/hgext/hgcia.py
--- a/hgext/hgcia.py
+++ b/hgext/hgcia.py
@@ -48,6 +48,10 @@ import email.Parser
 
 import socket, xmlrpclib
 from xml.sax import saxutils
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 socket_timeout = 30 # seconds
diff --git a/hgext/hgk.py b/hgext/hgk.py
--- a/hgext/hgk.py
+++ b/hgext/hgk.py
@@ -41,6 +41,10 @@ from mercurial.i18n import _
 
 cmdtable = {}
 command = cmdutil.command(cmdtable)
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 @command('debug-diff-tree',
diff --git a/hgext/highlight/__init__.py b/hgext/highlight/__init__.py
--- a/hgext/highlight/__init__.py
+++ b/hgext/highlight/__init__.py
@@ -24,6 +24,10 @@ The default is 'colorful'.
 import highlight
 from mercurial.hgweb import webcommands, webutil, common
 from mercurial import extensions, encoding
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 def filerevision_highlight(orig, web, tmpl, fctx):
diff --git a/hgext/histedit.py b/hgext/histedit.py
--- a/hgext/histedit.py
+++ b/hgext/histedit.py
@@ -181,6 +181,10 @@ from mercurial.i18n import _
 cmdtable = {}
 command = cmdutil.command(cmdtable)
 
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 # i18n: command names and abbreviations must remain untranslated
diff --git a/hgext/keyword.py b/hgext/keyword.py
--- a/hgext/keyword.py
+++ b/hgext/keyword.py
@@ -91,6 +91,10 @@ import os, re, tempfile
 
 cmdtable = {}
 command = cmdutil.command(cmdtable)
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 # hg commands that do not act on keywords
diff --git a/hgext/largefiles/__init__.py b/hgext/largefiles/__init__.py
--- a/hgext/largefiles/__init__.py
+++ b/hgext/largefiles/__init__.py
@@ -112,6 +112,10 @@ import proto
 import reposetup
 import uisetup as uisetupmod
 
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 reposetup = reposetup.reposetup
diff --git a/hgext/mq.py b/hgext/mq.py
--- a/hgext/mq.py
+++ b/hgext/mq.py
@@ -76,6 +76,10 @@ seriesopts = [('s', 'summary', None, _('
 
 cmdtable = {}
 command = cmdutil.command(cmdtable)
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 # force load strip extension formerly included in mq and import some utility
diff --git a/hgext/notify.py b/hgext/notify.py
--- a/hgext/notify.py
+++ b/hgext/notify.py
@@ -141,6 +141,10 @@ from mercurial.i18n import _
 from mercurial import patch, cmdutil, util, mail
 import fnmatch
 
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 # template for single changeset can include email headers.
diff --git a/hgext/pager.py b/hgext/pager.py
--- a/hgext/pager.py
+++ b/hgext/pager.py
@@ -59,6 +59,10 @@ import atexit, sys, os, signal, subproce
 from mercurial import commands, dispatch, util, extensions, cmdutil
 from mercurial.i18n import _
 
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 def _pagerfork(ui, p):
diff --git a/hgext/patchbomb.py b/hgext/patchbomb.py
--- a/hgext/patchbomb.py
+++ b/hgext/patchbomb.py
@@ -71,6 +71,10 @@ from mercurial.node import bin
 
 cmdtable = {}
 command = cmdutil.command(cmdtable)
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 def prompt(ui, prompt, default=None, rest=':'):
diff --git a/hgext/progress.py b/hgext/progress.py
--- a/hgext/progress.py
+++ b/hgext/progress.py
@@ -40,6 +40,10 @@ import time
 import threading
 
 from mercurial.i18n import _
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 from mercurial import encoding
diff --git a/hgext/purge.py b/hgext/purge.py
--- a/hgext/purge.py
+++ b/hgext/purge.py
@@ -30,6 +30,10 @@ import os
 
 cmdtable = {}
 command = cmdutil.command(cmdtable)
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 @command('purge|clean',
diff --git a/hgext/rebase.py b/hgext/rebase.py
--- a/hgext/rebase.py
+++ b/hgext/rebase.py
@@ -29,6 +29,10 @@ revignored = -3
 
 cmdtable = {}
 command = cmdutil.command(cmdtable)
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 def _savegraft(ctx, extra):
diff --git a/hgext/record.py b/hgext/record.py
--- a/hgext/record.py
+++ b/hgext/record.py
@@ -13,6 +13,10 @@ from mercurial import util
 
 cmdtable = {}
 command = cmdutil.command(cmdtable)
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 
diff --git a/hgext/relink.py b/hgext/relink.py
--- a/hgext/relink.py
+++ b/hgext/relink.py
@@ -13,6 +13,10 @@ import os, stat
 
 cmdtable = {}
 command = cmdutil.command(cmdtable)
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 @command('relink', [], _('[ORIGIN]'))
diff --git a/hgext/schemes.py b/hgext/schemes.py
--- a/hgext/schemes.py
+++ b/hgext/schemes.py
@@ -44,6 +44,10 @@ import os, re
 from mercurial import extensions, hg, templater, util
 from mercurial.i18n import _
 
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 
diff --git a/hgext/share.py b/hgext/share.py
--- a/hgext/share.py
+++ b/hgext/share.py
@@ -12,6 +12,10 @@ import errno
 
 cmdtable = {}
 command = cmdutil.command(cmdtable)
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 @command('share',
diff --git a/hgext/shelve.py b/hgext/shelve.py
--- a/hgext/shelve.py
+++ b/hgext/shelve.py
@@ -33,6 +33,10 @@ import errno
 
 cmdtable = {}
 command = cmdutil.command(cmdtable)
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 class shelvedfile(object):
diff --git a/hgext/strip.py b/hgext/strip.py
--- a/hgext/strip.py
+++ b/hgext/strip.py
@@ -11,6 +11,10 @@ from mercurial import repair, bookmarks,
 
 cmdtable = {}
 command = cmdutil.command(cmdtable)
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 def checksubstate(repo, baserev=None):
diff --git a/hgext/transplant.py b/hgext/transplant.py
--- a/hgext/transplant.py
+++ b/hgext/transplant.py
@@ -26,6 +26,10 @@ class TransplantError(error.Abort):
 
 cmdtable = {}
 command = cmdutil.command(cmdtable)
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 class transplantentry(object):
diff --git a/hgext/win32mbcs.py b/hgext/win32mbcs.py
--- a/hgext/win32mbcs.py
+++ b/hgext/win32mbcs.py
@@ -48,6 +48,10 @@ It is useful for the users who want to c
 import os, sys
 from mercurial.i18n import _
 from mercurial import util, encoding
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 _encoding = None                                # see extsetup
diff --git a/hgext/win32text.py b/hgext/win32text.py
--- a/hgext/win32text.py
+++ b/hgext/win32text.py
@@ -46,6 +46,10 @@ from mercurial.node import short
 from mercurial import util
 import re
 
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 # regexp for single LF without CR preceding.
diff --git a/hgext/zeroconf/__init__.py b/hgext/zeroconf/__init__.py
--- a/hgext/zeroconf/__init__.py
+++ b/hgext/zeroconf/__init__.py
@@ -31,6 +31,10 @@ from mercurial import ui, hg, encoding, 
 from mercurial import extensions
 from mercurial.hgweb import server as servermod
 
+# Note for extension authors: ONLY specify testedwith = 'internal' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
 testedwith = 'internal'
 
 # publish