From d802698d3e27a3cf091a56556df3562cc6ff996c Mon Sep 17 00:00:00 2001
From: Nobuyoshi Nakada <nobu@ruby-lang.org>
Date: Thu, 9 May 2019 10:01:31 +0900
Subject: Push the current (topic) branch to the remote upstream

---
 tool/vcs.rb | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/tool/vcs.rb b/tool/vcs.rb
index 8e6227685c..9310629089 100644
--- a/tool/vcs.rb
+++ b/tool/vcs.rb
@@ -510,6 +510,15 @@ class VCS
       dryrun = opts.fetch(:dryrun) {$DEBUG} if opts
       args = [COMMAND, "push"]
       args << "-n" if dryrun
+      (branch = cmd_read(%W"#{COMMAND} symbolic-ref --short HEAD")).chomp!
+      (upstream = cmd_read(%W"#{COMMAND} branch --list --format=%(upstream) #{branch}")).chomp!
+      while ref = upstream[%r"\Arefs/heads/(.*)", 1]
+        upstream = cmd_read(%W"#{COMMAND} branch --list --format=%(upstream) #{ref}")
+      end
+      unless %r"\Arefs/remotes/([^/]+)/(.*)" =~ upstream
+        raise "Upstream not found"
+      end
+      args << $1 << "HEAD:#$2"
       STDERR.puts(args.inspect) if dryrun
       system(*args) or return false
       true
-- 
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