CurlDownloadStrategy: dup mirror list before mutating it

Library/Homebrew/download_strategy.rb

@@ -67,9 +67,8 @@ class VCSDownloadStrategy < AbstractDownloadStrategy
 end
 
 class CurlDownloadStrategy < AbstractDownloadStrategy
-  def initialize name, resource
-    super
-    @mirrors = resource.mirrors
+  def mirrors
+    @mirrors ||= resource.mirrors.dup
   end
 
   def tarball_path
@@ -120,9 +119,9 @@ class CurlDownloadStrategy < AbstractDownloadStrategy
       puts "Already downloaded: #{tarball_path}"
     end
   rescue CurlDownloadStrategyError
-    raise if @mirrors.empty?
+    raise if mirrors.empty?
     puts "Trying a mirror..."
-    @url = @mirrors.shift
+    @url = mirrors.shift
     retry
   else
     tarball_path
@@ -170,7 +169,7 @@ class CurlDownloadStrategy < AbstractDownloadStrategy
   private
 
   def curl(*args)
-    args << '--connect-timeout' << '5' unless @mirrors.empty?
+    args << '--connect-timeout' << '5' unless mirrors.empty?
     super
   end
 

Library/Homebrew/test/test_resource.rb

@@ -75,8 +75,7 @@ class ResourceTests < Test::Unit::TestCase
     assert_empty @resource.mirrors
     @resource.mirror('foo')
     @resource.mirror('bar')
-    assert_equal 'foo', @resource.mirrors.shift
-    assert_equal 'bar', @resource.mirrors.shift
+    assert_equal %w{foo bar}, @resource.mirrors
   end
 
   def test_checksum_setters