handle restore of multiple asset manifests on rollback (#226)

* handle restore of multiple asset manifests on rollback

* cosmetic changes

* correctly copy sources to targets on asset rollback

* Update lib/capistrano/tasks/assets.rake

Co-authored-by: Matt Brictson <mattbrictson@users.noreply.github.com>

Co-authored-by: Matt Brictson <mattbrictson@users.noreply.github.com>

lib/capistrano/tasks/assets.rake

@@ -88,10 +88,15 @@ namespace :deploy do
     task :restore_manifest do
       on release_roles(fetch(:assets_roles)) do
         within release_path do
-          target = detect_manifest_path
-          source = release_path.join('assets_manifest_backup', File.basename(target))
-          if test "[[ -f #{source} && -f #{target} ]]"
-            execute :cp, source, target
+          targets = detect_manifest_path.split(' ')
+          sources = targets.map do |target|
+            release_path.join('assets_manifest_backup', File.basename(target))
+          end
+          if test(:ls, *sources) && test(:ls, *targets)
+            source_map = sources.zip(targets)
+            source_map.each do |source, target|
+              execute :cp, source, target
+            end
           else
             msg = 'Rails assets manifest file (or backup file) not found.'
             warn msg