pull: hold wlock for the full operation when --update is used

With now, the wlock is not held between the pull and the update. This can lead
to race condition and make logic checking to post pull results more complicated
(eg: with _afterlock).

mercurial/commands.py

@@ -4007,6 +4007,10 b' def pull(ui, repo, source="default", **o'
                         "so a rev cannot be specified.")
                 raise error.Abort(err)
 
+        wlock = util.nullcontextmanager()
+        if opts.get('update'):
+            wlock = repo.wlock()
+        with wlock:
         pullopargs.update(opts.get('opargs', {}))
         modheads = exchange.pull(repo, other, heads=revs,
                                  force=opts.get('force'),

tests/test-keyword.t

@@ -262,6 +262,7 b' Pull from bundle and trigger notify'
   adding file changes
   added 2 changesets with 3 changes to 3 files
   new changesets a2392c293916:ef63ca68695b
+  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
   MIME-Version: 1.0
   Content-Type: text/plain; charset="us-ascii"
   Content-Transfer-Encoding: 7bit
@@ -314,7 +315,6 b' Pull from bundle and trigger notify'
   +++ b/b	Thu Jan 01 00:00:00 1970 +0000
   @@ -0,0 +1,1 @@
   +ignore $Id$
-  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
 
   $ cp $HGRCPATH.nohooks $HGRCPATH