Merge branch 'stable-5.1' into stable-5.2

* stable-5.1:
  ObjectDirectory: extra logging on packfile exceptions

Change-Id: Id2fea30664d53b31ad026ee5ae06a5a24d731a52

org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/ObjectDirectory.java

 					// The hasObject call should have only touched the index,
 					// so any failure here indicates the index is unreadable
 					// by this process, and the pack is likewise not readable.
+					LOG.warn("Unable to read packfile " + p.getPackFile(), e);
 					removePack(p);
 				}
 			}
 		if ((e instanceof CorruptObjectException)
 				|| (e instanceof PackInvalidException)) {
 			warnTmpl = JGitText.get().corruptPack;
+			LOG.warn("Packfile " + p.getPackFile() + " is corrupted", e);
 			// Assume the pack is corrupted, and remove it from the list.
 			removePack(p);
 		} else if (e instanceof FileNotFoundException) {