diff --git a/Library/Homebrew/dev-cmd/test-bot.rb b/Library/Homebrew/dev-cmd/test-bot.rb
index 8474e1f88ce493f99abeacd0687e98f7430e1d3e..4295639d22bb993e6f34e04dc39e8fbdf2afe36f 100644
--- a/Library/Homebrew/dev-cmd/test-bot.rb
+++ b/Library/Homebrew/dev-cmd/test-bot.rb
@@ -857,7 +857,11 @@ module Homebrew
       safe_system "brew", "pull", "--clean", pull_pr
     end
 
-    system "brew", "bottle", "--merge", "--write", *json_files
+    if ENV["UPSTREAM_BOTTLE_KEEP_OLD"]
+      system "brew", "bottle", "--merge", "--write", "--keep-old", *json_files
+    else
+      system "brew", "bottle", "--merge", "--write", *json_files
+    end
 
     remote = "git@github.com:BrewTestBot/homebrew-#{tap.repo}.git"
     git_tag = pr ? "pr-#{pr}" : "testing-#{number}"