Fix MissingObjectException in change set

An MissingObjectException occurs when any node contains added (or
deleted) resource.

Change-Id: Iecc6f5ffd8e09421c759bf80d8848dfb7d57ff6c
Signed-off-by: Dariusz Luksza <dariusz@luksza.org>

3 files changed, 26 insertions, 8 deletions

diff --git a/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/synchronize/mapping/GitTreeTraversal.java b/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/synchronize/mapping/GitTreeTraversal.java
index 467f18fbc3..5b9be65e25 100644
--- a/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/synchronize/mapping/GitTreeTraversal.java
+++ b/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/synchronize/mapping/GitTreeTraversal.java
@@ -8,6 +8,8 @@
  *******************************************************************************/
 package org.eclipse.egit.ui.internal.synchronize.mapping;
 
+import static org.eclipse.jgit.lib.ObjectId.zeroId;
+
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
@@ -47,6 +49,9 @@ class GitTreeTraversal extends ResourceTraversal {
 
 	private static IResource[] getResourcesImpl(Repository repo, IPath path,
 			AnyObjectId baseId, AnyObjectId remoteId) {
+		if (remoteId.equals(zeroId()))
+			return new IResource[0];
+
 		TreeWalk tw = new TreeWalk(repo);
 		List<IResource> result = new ArrayList<IResource>();
 		IWorkspaceRoot root = ResourcesPlugin.getWorkspace().getRoot();
@@ -55,7 +60,8 @@ class GitTreeTraversal extends ResourceTraversal {
 		tw.setRecursive(false);
 		tw.setFilter(TreeFilter.ANY_DIFF);
 		try {
-			tw.addTree(baseId);
+			if (!baseId.equals(zeroId()))
+				tw.addTree(baseId);
 			int actualNth = tw.addTree(remoteId);
 
 			while (tw.next()) {
diff --git a/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/synchronize/model/GitModelCommit.java b/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/synchronize/model/GitModelCommit.java
index 9e4c56add5..5b8c92cd54 100644
--- a/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/synchronize/model/GitModelCommit.java
+++ b/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/synchronize/model/GitModelCommit.java
@@ -197,7 +197,7 @@ public class GitModelCommit extends GitModelObject {
 		if (baseNth > -1)
 			objBaseId = tw.getObjectId(baseNth);
 		else
-			objBaseId = null;
+			objBaseId = ObjectId.zeroId();
 
 		ObjectId objRemoteId = tw.getObjectId(actualNth);
 		ObjectId objAncestorId = tw.getObjectId(ancestorNth);
diff --git a/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/synchronize/model/GitModelTree.java b/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/synchronize/model/GitModelTree.java
index e47a109435..65ae9a2b0b 100644
--- a/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/synchronize/model/GitModelTree.java
+++ b/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/synchronize/model/GitModelTree.java
@@ -8,6 +8,8 @@
  *******************************************************************************/
 package org.eclipse.egit.ui.internal.synchronize.model;
 
+import static org.eclipse.jgit.lib.ObjectId.zeroId;
+
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
@@ -112,9 +114,17 @@ public class GitModelTree extends GitModelCommit {
 		List<GitModelObject> result = new ArrayList<GitModelObject>();
 
 		try {
-			int ancestorNth = tw.addTree(ancestorId);
-			int baseNth = tw.addTree(baseId);
-			int remoteNth = tw.addTree(remoteId);
+			int ancestorNth = -1;
+			if (!ancestorId.equals(zeroId()))
+				ancestorNth = tw.addTree(ancestorId);
+
+			int baseNth = -1;
+			if (!baseId.equals(zeroId()))
+				baseNth = tw.addTree(baseId);
+
+			int remoteNth = -1;
+			if (!remoteId.equals(zeroId()))
+				remoteNth = tw.addTree(remoteId);
 
 			while (tw.next()) {
 				GitModelObject obj = createChildren(tw, ancestorNth, baseNth,
@@ -132,9 +142,11 @@ public class GitModelTree extends GitModelCommit {
 	private GitModelObject createChildren(TreeWalk tw, int ancestorNth,
 			int baseNth, int remoteNth) throws IOException {
 		String objName = tw.getNameString();
-		ObjectId objBaseId = tw.getObjectId(baseNth);
-		ObjectId objRemoteId = tw.getObjectId(remoteNth);
-		ObjectId objAncestorId = tw.getObjectId(ancestorNth);
+		ObjectId objBaseId = baseNth != -1 ? tw.getObjectId(baseNth) : zeroId();
+		ObjectId objRemoteId = remoteNth != -1 ? tw.getObjectId(remoteNth)
+				: zeroId();
+		ObjectId objAncestorId = ancestorNth != -1 ? tw
+				.getObjectId(ancestorNth) : zeroId();
 		int objectType = tw.getFileMode(remoteNth).getObjectType();
 
 		if (objectType == Constants.OBJ_BLOB)