fix(index): Write a revision and revise predecessors on both source...

...and target for "net zero" changes; don't mention the object in the
corresponding commit document however.

commons/com.b2international.index/src/com/b2international/index/revision/StagingArea.java

@@ -425,11 +425,7 @@ private Commit doCommit(String commitGroupId, long timestamp, String author, Str
 				if (object instanceof Revision) {
 					RevisionDiff revisionDiff = value.getDiff();
 					final Revision rev = revisionDiff.newRevision;
-
-					if (!revisionDiff.hasChanges()) {
-						return;
-					}
-
+
 					if (isMerge()) {
 						revisionsToReviseOnMergeSource.put(rev.getClass(), rev.getId());
 					}
@@ -439,7 +435,11 @@ private Commit doCommit(String commitGroupId, long timestamp, String author, Str
 					}
 
 					writer.put(rev);
-
+
+					if (!revisionDiff.hasChanges()) {
+						return;
+					}
+
 					// register component as changed in commit doc
 					ObjectId containerId = checkNotNull(rev.getContainerId(), "Missing containerId for revision: %s", rev);
 					ObjectId objectId = rev.getObjectId();