Merge pull request #15881 from samford/livecheck/guard-watchlist-test

dev-cmd/livecheck: avoid watchlist in test

Library/Homebrew/test/dev-cmd/livecheck_spec.rb

@@ -20,7 +20,7 @@ describe "brew livecheck" do
   end
 
   it "gives an error when no arguments are given and there's no watchlist", :integration_test do
-    expect { brew "livecheck" }
+    expect { brew "livecheck", "HOMEBREW_LIVECHECK_WATCHLIST" => ".this_should_not_exist" }
       .to output(/Invalid usage: A watchlist file is required when no arguments are given\./).to_stderr
       .and not_to_output.to_stdout
       .and be_a_failure