public function execute(Context $context)
 {
     // this was filled by the builder
     $filesModified = $context->getFilesModified();
     $filesDeleted = $context->getFilesDeleted();
     if (false === $context->isFullDeploy()) {
         $diff = $this->repository->diff($context->getRemoteVersion(), $context->getVersion());
         $subselectionModified = new FileCollection($context->getBuilddir());
         foreach ($diff as $fileinfo) {
             if (Status::ADDED === $fileinfo->getStatus()) {
                 $subselectionModified[] = $fileinfo->getPathname();
             } elseif (Status::MODIFIED === $fileinfo->getStatus()) {
                 $subselectionModified[] = $fileinfo->getPathname();
             } elseif (Status::DELETED === $fileinfo->getStatus()) {
                 $filesDeleted->add($fileinfo->getPathname(), true);
             } else {
                 // @todo handle other cases if they actually exist
             }
         }
         foreach ($this->derivedFiles as $derivable) {
             $source = $derivable['source'];
             $derived = $derivable['derived'];
             if ($subselectionModified->has($source)) {
                 $subselectionModified->add($derived);
             }
         }
         // only keep files that are changed
         $filesModified->intersect($subselectionModified);
         //            if (0 === count($filesAdded) && count($subselectionAdded) > 0) {
         //                // hmm.. so files have changed but nothing to deploy
         //                // it looks like we forgot to specify some derived files
         //                // @todo inform the user about this?
         //            }
         // @todo we could also check here if all files are accounted for (maybe
         //       some files were deleted and not told to us by setting it in
         //       the `removes` config?) in other words: file_exists on all files?
     } else {
         foreach ($this->derivedFiles as $derivable) {
             $source = $derivable['source'];
             $derived = $derivable['derived'];
             if ($filesModified->has($source)) {
                 $filesModified->add($derived);
             }
         }
     }
     // never upload the conveyor configuration!
     $filesModified->remove('conveyor.yml');
     // validate result, throw exception when we have nothing to deploy
     if (0 === count($filesModified) && 0 === count($filesDeleted)) {
         throw new EmptyChangesetException();
     }
     $context->setFilesModified($filesModified);
     $context->setFilesDeleted($filesDeleted);
 }