--- a/hgext3rd/topic/flow.py	Wed Nov 01 16:26:33 2017 +0100
+++ b/hgext3rd/topic/flow.py	Wed Nov 01 16:23:13 2017 +0100
@@ -1,9 +1,13 @@
 from __future__ import absolute_import
 
 from mercurial import (
+    commands,
     error,
+    exchange,
+    extensions,
     node,
     phases,
+    util,
 )
 
 from mercurial.i18n import _
@@ -25,3 +29,41 @@
         cl = repo.changelog
         nodes = [cl.node(r) for r in topublish]
         repo._phasecache.advanceboundary(repo, tr, phases.public, nodes)
+
+def wrappush(orig, repo, remote, *args, **kwargs):
+    """interpret the --publish flag and pass it to the push operation"""
+    newargs = kwargs.copy()
+    if kwargs.pop('publish', False):
+        opargs = kwargs.get('opargs')
+        if opargs is None:
+            opargs = {}
+        newargs['opargs'] = opargs.copy()
+        newargs['opargs']['publish'] = True
+    return orig(repo, remote, *args, **newargs)
+
+def extendpushoperation(orig, *args, **kwargs):
+    publish = kwargs.pop('publish', False)
+    op = orig(*args, **kwargs)
+    op.publish = publish
+    return op
+
+def wrapphasediscovery(orig, pushop):
+    orig(pushop)
+    if pushop.publish:
+        if not util.safehasattr(pushop, 'remotephases'):
+            msg = _('--publish flag only supported from Mercurial 4.4 and higher')
+            raise error.Abort(msg)
+        if not pushop.remotephases.publishing:
+            unfi = pushop.repo.unfiltered()
+            droots = pushop.remotephases.draftroots
+            revset = '%ln and (not public() or %ln::)'
+            future = list(unfi.set(revset, pushop.futureheads, droots))
+            pushop.outdatedphases = future
+
+def installpushflag(ui):
+    entry = extensions.wrapcommand(commands.table, 'push', wrappush)
+    entry[1].append(('', 'publish', False,
+                    _('push the changeset as public')))
+    extensions.wrapfunction(exchange, 'pushoperation', extendpushoperation)
+    extensions.wrapfunction(exchange, '_pushdiscoveryphase', wrapphasediscovery)
+    exchange.pushdiscoverymapping['phase'] = exchange._pushdiscoveryphase