incoming: delay pager activation until right before printing changes

incoming: delay pager activation until right before printing changes

This prevents authentication and other brief status messages from
being paged.

--- a/mercurial/commands.py	Sat Feb 18 21:30:28 2017 +1100
+++ b/mercurial/commands.py	Tue Feb 21 10:53:13 2017 -0500
@@ -3210,7 +3210,6 @@
             cmdutil.displaygraph(ui, repo, revdag, displayer,
                                  graphmod.asciiedges)
 
-        ui.pager('incoming')
         hg._incoming(display, lambda: 1, ui, repo, source, opts, buffered=True)
         return 0
 
@@ -3230,7 +3229,6 @@
 
     repo._subtoppath = ui.expandpath(source)
     try:
-        ui.pager('incoming')
         return hg.incoming(ui, repo, source, opts)
     finally:
         del repo._subtoppath

--- a/mercurial/hg.py	Sat Feb 18 21:30:28 2017 +1100
+++ b/mercurial/hg.py	Tue Feb 21 10:53:13 2017 -0500
@@ -804,7 +804,7 @@
         if not chlist:
             ui.status(_("no changes found\n"))
             return subreporecurse()
-
+        ui.pager('incoming')
         displayer = cmdutil.show_changeset(ui, other, opts, buffered)
         displaychlist(other, chlist, displayer)
         displayer.close()