Respond with shallow-info before wanted-refs

When fetching with protocol v2, git expects the shallow-info section to
appear before wanted-refs if both appear in the response. Teach
UploadPack to do this.

Change-Id: Ie26a91edcce5d27a1d727d7fba5c30e1144e118b
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>

org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/UploadPackTest.java

@@ -1367,13 +1367,13 @@ public class UploadPackTest {
 			PacketLineIn.END);
 		PacketLineIn pckIn = new PacketLineIn(recvStream);
 
-		// wanted-refs appears first, then shallow-info.
-		assertThat(pckIn.readString(), is("wanted-refs"));
-		assertThat(pckIn.readString(), is(child.toObjectId().getName() + " refs/heads/branch1"));
-		assertThat(pckIn.readString(), theInstance(PacketLineIn.DELIM));
+		// shallow-info appears first, then wanted-refs.
 		assertThat(pckIn.readString(), is("shallow-info"));
 		assertThat(pckIn.readString(), is("shallow " + child.toObjectId().getName()));
 		assertThat(pckIn.readString(), theInstance(PacketLineIn.DELIM));
+		assertThat(pckIn.readString(), is("wanted-refs"));
+		assertThat(pckIn.readString(), is(child.toObjectId().getName() + " refs/heads/branch1"));
+		assertThat(pckIn.readString(), theInstance(PacketLineIn.DELIM));
 		assertThat(pckIn.readString(), is("packfile"));
 		parsePack(recvStream);
 		assertTrue(client.hasObject(child.toObjectId()));

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

@@ -1083,18 +1083,6 @@ public class UploadPack {
 		}
 
 		if (doneReceived || okToGiveUp()) {
-			if (!wantedRefs.isEmpty()) {
-				if (sectionSent) {
-					pckOut.writeDelim();
-				}
-				pckOut.writeString("wanted-refs\n"); //$NON-NLS-1$
-				for (Map.Entry<String, ObjectId> entry : wantedRefs.entrySet()) {
-					pckOut.writeString(entry.getValue().getName() + ' ' +
-							entry.getKey() + '\n');
-				}
-				sectionSent = true;
-			}
-
 			if (shallowCommits != null) {
 				if (sectionSent)
 					pckOut.writeDelim();
@@ -1108,6 +1096,18 @@ public class UploadPack {
 				sectionSent = true;
 			}
 
+			if (!wantedRefs.isEmpty()) {
+				if (sectionSent) {
+					pckOut.writeDelim();
+				}
+				pckOut.writeString("wanted-refs\n"); //$NON-NLS-1$
+				for (Map.Entry<String, ObjectId> entry : wantedRefs.entrySet()) {
+					pckOut.writeString(entry.getValue().getName() + ' ' +
+							entry.getKey() + '\n');
+				}
+				sectionSent = true;
+			}
+
 			if (sectionSent)
 				pckOut.writeDelim();
 			pckOut.writeString("packfile\n"); //$NON-NLS-1$