delete hasFile check

this is not needed as the lib checks the file existance on
`getFileContent` and gives a nice eror message if it does not exist

tests/acceptance/features/bootstrap/ArchiverContext.php

@@ -102,11 +102,6 @@ class ArchiverContext implements Context {
 		\file_put_contents($tempFile, $this->featureContext->getResponse()->getBody()->getContents());
 		$archive = UnifiedArchive::open($tempFile);
 		foreach ($expectedFiles->getHash() as $expectedFile) {
-			Assert::assertTrue(
-				$archive->hasFile($expectedFile['name']),
-				__METHOD__ .
-				" archive does not contain '" . $expectedFile['name'] . "'"
-			);
 			Assert::assertEquals(
 				$expectedFile['content'],
 				$archive->getFileContent($expectedFile['name']),