[PATCH V3] dispatch: flush ui before returning from dispatch

[Jun Wu]

# HG changeset patch
# User Jun Wu <quark at fb.com>
# Date 1457953594 0
#      Mon Mar 14 11:06:34 2016 +0000
# Node ID 5becd975aa2bd1945471c997f9c6a2738bc96568
# Parent  4c950800184ec1e943967d3ed4a410a4f700d900
dispatch: flush ui before returning from dispatch

A chg client may exit after received the result from runcommand. It is
necessary to do a flush to make sure the warning message is printed out
and the process waiting for the chg client will actually see the output.

This helps chg to pass test-alias.t.

diff --git a/mercurial/dispatch.py b/mercurial/dispatch.py
--- a/mercurial/dispatch.py
+++ b/mercurial/dispatch.py
@@ -129,6 +129,7 @@
         ret = -1
     finally:
         duration = time.time() - starttime
+        req.ui.flush()
         req.ui.log("commandfinish", "%s exited %s after %0.2f seconds\n",
                    msg, ret or 0, duration)
     return ret