UploadPack: Report invalid want lines with ERR

Instead of aborting hard with a server-side exception, report an error
to the client with "ERR %s" in a context where the client is expecting
ACK/NAK.  Older clients will report this text to the user, but newer
ones know how to format this message in a more user-friendly way.

Change-Id: I1879b38988ba66f648c069c10dbfa14c3f34adb2
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

org.eclipse.jgit/resources/org/eclipse/jgit/JGitText.properties

@@ -303,7 +303,6 @@ notASCIIString=Not ASCII string: {0}
 notAuthorized=not authorized
 notAValidPack=Not a valid pack {0}
 notFound=not found.
-notValid={0} not valid
 nothingToFetch=Nothing to fetch.
 nothingToPush=Nothing to push.
 notMergedExceptionMessage=Branch was not deleted as it has not been merged yet; use the force option to delete it anyway
@@ -466,6 +465,7 @@ updatingRefFailed=Updating the ref {0} to {1} failed. ReturnCode from RefUpdate.
 uriNotFound={0} not found
 userConfigFileInvalid=User config file {0} invalid {1}
 walkFailure=Walk failure.
+wantNotValid=want {0} not valid
 windowSizeMustBeLesserThanLimit=Window size must be < limit
 windowSizeMustBePowerOf2=Window size must be power of 2
 writeTimedOut=Write timed out

org.eclipse.jgit/src/org/eclipse/jgit/JGitText.java

@@ -363,7 +363,6 @@ public class JGitText extends TranslationBundle {
 	/***/ public String notAuthorized;
 	/***/ public String notAValidPack;
 	/***/ public String notFound;
-	/***/ public String notValid;
 	/***/ public String nothingToFetch;
 	/***/ public String nothingToPush;
 	/***/ public String notMergedExceptionMessage;
@@ -526,6 +525,7 @@ public class JGitText extends TranslationBundle {
 	/***/ public String uriNotFound;
 	/***/ public String userConfigFileInvalid;
 	/***/ public String walkFailure;
+	/***/ public String wantNotValid;
 	/***/ public String windowSizeMustBeLesserThanLimit;
 	/***/ public String windowSizeMustBePowerOf2;
 	/***/ public String writeTimedOut;

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

@@ -511,10 +511,12 @@ public class UploadPack {
 				try {
 					obj = q.next();
 				} catch (MissingObjectException notFound) {
-					if (wantIds.contains(notFound.getObjectId())) {
-						throw new PackProtocolException(
-								MessageFormat.format(JGitText.get().notValid,
-										notFound.getMessage()), notFound);
+					ObjectId id = notFound.getObjectId();
+					if (wantIds.contains(id)) {
+						String msg = MessageFormat.format(
+								JGitText.get().wantNotValid, id.name());
+						pckOut.writeString("ERR " + msg);
+						throw new PackProtocolException(msg, notFound);
 					}
 					continue;
 				}
@@ -526,8 +528,10 @@ public class UploadPack {
 				//
 				if (wantIds.remove(obj)) {
 					if (!advertised.contains(obj)) {
-						throw new PackProtocolException(MessageFormat.format(
-								JGitText.get().notValid, obj.name()));
+						String msg = MessageFormat.format(
+								JGitText.get().wantNotValid, obj.name());
+						pckOut.writeString("ERR " + msg);
+						throw new PackProtocolException(msg);
 					}
 
 					if (!obj.has(WANT)) {