Added closing of zip file to avoid VM going into hindenburg mode

Zip files are dangerous things

git-svn-id: https://svn.apache.org/repos/asf/maven/plugins/trunk@1626500 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/src/test/java/org/apache/maven/plugins/repository/testutil/Assertions.java b/src/test/java/org/apache/maven/plugins/repository/testutil/Assertions.java
index 06c987d..cb57020 100644
--- a/src/test/java/org/apache/maven/plugins/repository/testutil/Assertions.java
+++ b/src/test/java/org/apache/maven/plugins/repository/testutil/Assertions.java
@@ -56,6 +56,7 @@
             }
         }
 
+        zf.close();
         if ( !missing.isEmpty() || !banned.isEmpty() )
         {
             StringBuilder msg = new StringBuilder();