Silence non-externalized string warning in PackParser

Change-Id: I1a4181fc292c42157c69479f71c7674b2e00d2ce
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

org.eclipse.jgit/src/org/eclipse/jgit/transport/PackParser.java

@@ -812,7 +812,7 @@ public abstract class PackParser {
 
 		for (final DeltaChain base : missing) {
 			if (base.head != null)
-				throw new MissingObjectException(base, "delta base");
+				throw new MissingObjectException(base, "delta base"); //$NON-NLS-1$
 		}
 
 		onEndThinPack();