update-test: tweak master not updated check.

Loosen this a bit; we don't necessarily expect the end commit is the one
we're looking for, just that it has changed from the start commit (i.e.
some sort of update has occurred).

Addresses some false negatives on `master` branch merges that weren't
present on the PR commits.

1 files changed, 2 insertions, 2 deletions

diff --git a/Library/Homebrew/dev-cmd/update-test.rb b/Library/Homebrew/dev-cmd/update-test.rb
index 84de08a7f..cb2120216 100644
--- a/Library/Homebrew/dev-cmd/update-test.rb
+++ b/Library/Homebrew/dev-cmd/update-test.rb
@@ -15,7 +15,7 @@ module Homebrew
       Utils.popen_read("git", "rev-list", "-n1", "--before=#{date}", "origin/master").chomp
     else
       Utils.popen_read("git", "rev-parse", "origin/master").chomp
-     end
+    end
     start_sha1 = Utils.popen_read("git", "rev-parse", start_sha1).chomp
     end_sha1 = Utils.popen_read("git", "rev-parse", "HEAD").chomp
 
@@ -49,7 +49,7 @@ module Homebrew
       oh1 "Running brew update..."
       safe_system "brew", "update", "--verbose"
       actual_end_sha1 = Utils.popen_read("git", "rev-parse", "master").chomp
-      if actual_end_sha1 != end_sha1
+      if start_sha1 != end_sha1 && start_sha1 == actual_end_sha1
         raise <<-EOS.undent
           brew update didn't update master!
           Start commit:        #{start_sha1}