findbugs: check what is returned by mkdirs

git-svn-id: https://svn.apache.org/repos/asf/felix/trunk@1074957 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/dependencymanager/test/src/test/java/org/apache/felix/dm/test/BundleGenerator.java b/dependencymanager/test/src/test/java/org/apache/felix/dm/test/BundleGenerator.java
index 9c28af7..48368cb 100644
--- a/dependencymanager/test/src/test/java/org/apache/felix/dm/test/BundleGenerator.java
+++ b/dependencymanager/test/src/test/java/org/apache/felix/dm/test/BundleGenerator.java
@@ -20,9 +20,9 @@
 
 import java.io.File;
 import java.io.FileWriter;
+import java.io.IOException;
 import java.io.PrintWriter;
 import java.net.URL;
-import java.util.HashSet;
 import java.util.Properties;
 
 import aQute.lib.osgi.Analyzer;
@@ -79,9 +79,12 @@
             // Check if the system tmp dir exists
 
             File tmp = new File(System.getProperty("java.io.tmpdir"));
-            if (tmp != null && !tmp.exists())
+            if (!tmp.exists())
             {
-                tmp.mkdirs();
+                if (! tmp.mkdirs())
+                {
+                    throw new IOException("Could not create temporary directory: " + tmp);
+                }
             }
 
             // Deduce the classpath from Export-Package, or Private-Package headers.