Fix reference repositories on Windows.

Windows git did not look-up the alternative object directory if the
alternates file ended with \n, this patch simply changes println to
print for that file. That fixed all my issues with alternates.

src/main/java/org/jenkinsci/plugins/gitclient/CliGitAPIImpl.java

@@ -324,7 +324,7 @@ else if (!referencePath.isDirectory())
                                 File alternates = new File(workspace, ".git/objects/info/alternates");
                                 PrintWriter w = new PrintWriter(alternates);
                                 // git implementations on windows also use 
-                                w.println(objectsPath.getAbsolutePath().replace('\\', '/'));
+                                w.print(objectsPath.getAbsolutePath().replace('\\', '/'));
                                 w.close();
                             } catch (FileNotFoundException e) {
                                 listener.error("Failed to setup reference");