File.renameTo behaves differently on Unix and Windows

On Windows renameTo will not overwrite a file, so it must be deleted
first. The fix for Bug 402834 did not account for that.

Bug: 403685
Change-Id: I3453342c17e064dcb50906a540172978941a10a6

org.eclipse.jgit/src/org/eclipse/jgit/dircache/DirCacheCheckout.java

@@ -1126,17 +1126,13 @@ public class DirCacheCheckout {
 					fs.setExecute(tmpFile, false);
 			}
 		}
-		if (!tmpFile.renameTo(f)) {
-			// tried to rename which failed. Let' delete the target file and try
-			// again
-			FileUtils.delete(f, FileUtils.EMPTY_DIRECTORIES_ONLY
-					| FileUtils.RECURSIVE);
-			if (!tmpFile.renameTo(f)) {
+		try {
+			FileUtils.rename(tmpFile, f);
+		} catch (IOException e) {
 			throw new IOException(MessageFormat.format(
 					JGitText.get().couldNotWriteFile, tmpFile.getPath(),
 					f.getPath()));
 		}
-		}
 		entry.setLastModified(f.lastModified());
 		if (opt.getAutoCRLF() != AutoCRLF.FALSE)
 			entry.setLength(f.length()); // AutoCRLF wants on-disk-size