dispatch: write shell alias output to ui out descriptor

mercurial/dispatch.py

@@ -276,7 +276,7 b' class cmdalias(object):'
                 replace['0'] = self.name
                 replace['@'] = ' '.join(args)
                 cmd = util.interpolate(r'\$', replace, cmd, escape_prefix=True)
-                return util.system(cmd, environ=env)
+                return util.system(cmd, environ=env, out=ui.fout)
             self.fn = fn
             return
 

mercurial/util.py

@@ -354,7 +354,7 b' def system(cmd, environ={}, cwd=None, on'
     env = dict(os.environ)
     env.update((k, py2shell(v)) for k, v in environ.iteritems())
     env['HG'] = hgexecutable()
-    if out is None:
+    if out is None or out == sys.__stdout__:
         rc = subprocess.call(cmd, shell=True, close_fds=closefds,
                              env=env, cwd=cwd)
     else: