Print error message to log when plugin loader fails to close JAR file

Change-Id: Ic113b7759e094bd18c8c68767d85a25044400cb4
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/plugins/CleanupHandle.java b/gerrit-server/src/main/java/com/google/gerrit/server/plugins/CleanupHandle.java
index b04f337..593f2c9 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/plugins/CleanupHandle.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/plugins/CleanupHandle.java
@@ -32,6 +32,7 @@
     try {
       jarFile.close();
     } catch (IOException err) {
+      PluginLoader.log.error("Cannot close " + jarFile.getName(), err);
     }
     if (!tmpFile.delete() && tmpFile.exists()) {
       PluginLoader.log.warn("Cannot delete " + tmpFile.getAbsolutePath()