Merge pull request #20283 from Homebrew/skip-concurrent-fetch-fix-tests

Fix some stdout issues with concurrence

Author: MikeMcQuaid

Library/Homebrew/download_queue.rb

@@ -36,7 +36,9 @@ def enqueue(downloadable)
 
     sig { void }
     def fetch
-      if concurrency == 1
+      return if downloads.empty?
+
+      if concurrency == 1 || downloads.one?
         downloads.each do |downloadable, promise|
           promise.wait!
         rescue ChecksumMismatchError => e

Library/Homebrew/test/cmd/install_spec.rb

@@ -67,7 +67,7 @@ def install
     # Ignore dependencies, because we'll try to resolve requirements in build.rb
     # and there will be the git requirement, but we cannot instantiate git
     # formula since we only have testball1 formula.
-    expect { brew "install", "testball1", "--HEAD", "--ignore-dependencies" }
+    expect { brew "install", "testball1", "--HEAD", "--ignore-dependencies", "HOMEBREW_DOWNLOAD_CONCURRENCY" => "1" }
       .to output(%r{#{HOMEBREW_CELLAR}/testball1/HEAD-d5eb689}o).to_stdout
       .and output(/Cloning into/).to_stderr
       .and be_a_success