[PATCH 3 of 7] dispatch: set a blockedtag when running an external alias

[Simon Farnsworth]

# HG changeset patch
# User Simon Farnsworth <simonfar at fb.com>
# Date 1488799544 28800
#      Mon Mar 06 03:25:44 2017 -0800
# Node ID 6cb267dc6b8156333413b6bbadc819807d73241c
# Parent  1c0e78f6c4db0c43799ee7d2fe68290c9f172849
dispatch: set a blockedtag when running an external alias

diff --git a/mercurial/dispatch.py b/mercurial/dispatch.py
--- a/mercurial/dispatch.py
+++ b/mercurial/dispatch.py
@@ -354,7 +354,8 @@
                         return ''
                 cmd = re.sub(r'\$(\d+|\$)', _checkvar, self.definition[1:])
                 cmd = aliasinterpolate(self.name, args, cmd)
-                return ui.system(cmd, environ=env)
+                return ui.system(cmd, environ=env,
+                                 blockedtag='alias_%s' % self.name)
             self.fn = fn
             return