Use RawParseUtils.prevLF in RebaseCommand

As noticed by Robin Rosenberg in review of
I4eb87c850078ca187b38b81cc91c92afb1176945.

Change-Id: If96d66b6c025ad8f2f47829c933f3c65ab6cbeef
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

org.eclipse.jgit/src/org/eclipse/jgit/api/RebaseCommand.java

@@ -1250,10 +1250,8 @@ public class RebaseCommand extends GitCommand<RebaseResult> {
 				throws IOException {
 			byte[] content = IO.readFully(new File(directory, fileName));
 			// strip off the last LF
-			int end = content.length;
-			while (0 < end && content[end - 1] == '\n')
-				end--;
-			return RawParseUtils.decode(content, 0, end);
+			int end = RawParseUtils.prevLF(content, content.length);
+			return RawParseUtils.decode(content, 0, end + 1);
 		}
 
 		private static void createFile(File parentDir, String name,