Use JPG source, otherwise we have problems with Alpha conversion in OpenJDK.

https://stackoverflow.com/questions/3432388/imageio-not-able-to-write-a-jpeg-file

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1855668 13f79535-47bb-0310-9956-ffa450edef68

src/testcases/org/apache/poi/hssf/usermodel/TestBugs.java

@@ -2932,7 +2932,7 @@ public final class TestBugs extends BaseTestBugzillaIssues {
         Workbook wb = HSSFTestDataSamples.openSampleWorkbook("46515.xls");
 
         // Get structure from webservice
-        String urlString = "http://poi.apache.org/images/project-header.png";
+        String urlString = "http://poi.apache.org/components/spreadsheet/images/calendar.jpg";
         URL structURL = new URL(urlString);
         BufferedImage bimage;
         try {