ReceivePack: catch InvalidObjectIdException while parsing shallow

The "shallow $id" parsing can also throw InvalidObjectIdException,
just like parseCommand. Move it into its own method with a proper
try-catch block to convert to the checked PackProtocolException.

Change-Id: I6839b95f0bc4fbf4d2c213331ebb9bd24ab2af65

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

@@ -1093,7 +1093,7 @@ public abstract class BaseReceivePack {
 				}
 
 				if (line.length() >= 48 && line.startsWith("shallow ")) { //$NON-NLS-1$
-					clientShallowCommits.add(ObjectId.fromString(line.substring(8, 48)));
+					parseShallow(line.substring(8, 48));
 					continue;
 				}
 
@@ -1133,6 +1133,16 @@ public abstract class BaseReceivePack {
 		}
 	}
 
+	private void parseShallow(String idStr) throws PackProtocolException {
+		ObjectId id;
+		try {
+			id = ObjectId.fromString(idStr);
+		} catch (InvalidObjectIdException e) {
+			throw new PackProtocolException(e.getMessage(), e);
+		}
+		clientShallowCommits.add(id);
+	}
+
 	static ReceiveCommand parseCommand(String line) throws PackProtocolException {
           if (line == null || line.length() < 83) {
 			throw new PackProtocolException(