From c3bf9bda58aba514259d45972a5172e8801d5c65 Mon Sep 17 00:00:00 2001
From: Mike McQuaid <mike@mikemcquaid.com>
Date: Tue, 28 Mar 2017 15:31:16 +0100
Subject: [PATCH] update-test: improve error handling.

Fail if the start or end commit are missing and retry finding the
previous tag by fetching all tags if they are missing.

This should fix CI on the current Homebrew/brew `master` branch.

Closes #2404.
---
 Library/Homebrew/dev-cmd/update-test.rb | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/Library/Homebrew/dev-cmd/update-test.rb b/Library/Homebrew/dev-cmd/update-test.rb
index 2ff1686698..3cf095f2b2 100644
--- a/Library/Homebrew/dev-cmd/update-test.rb
+++ b/Library/Homebrew/dev-cmd/update-test.rb
@@ -33,12 +33,24 @@ module Homebrew
     elsif date = ARGV.value("before")
       Utils.popen_read("git", "rev-list", "-n1", "--before=#{date}", "origin/master").chomp
     elsif ARGV.include?("--to-tag")
-      Utils.popen_read("git", "tag", "--list", "--sort=-version:refname").lines[1].chomp
+      previous_tag =
+        Utils.popen_read("git", "tag", "--list", "--sort=-version:refname").lines[1]
+      unless previous_tag
+        safe_system "git", "fetch", "--tags"
+        previous_tag =
+          Utils.popen_read("git", "tag", "--list", "--sort=-version:refname").lines[1]
+      end
+      previous_tag.to_s.chomp
     else
       Utils.popen_read("git", "rev-parse", "origin/master").chomp
     end
+    odie "Could not find start commit!" if start_commit.empty?
+
     start_commit = Utils.popen_read("git", "rev-parse", start_commit).chomp
+    odie "Could not find start commit!" if start_commit.empty?
+
     end_commit = Utils.popen_read("git", "rev-parse", "HEAD").chomp
+    odie "Could not find end commit!" if end_commit.empty?
 
     puts "Start commit: #{start_commit}"
     puts "End   commit: #{end_commit}"