Make sure dropdown excludes all choice fields (not just children of MRQs).

problem_builder/instructor_tool.py

@@ -189,6 +189,7 @@ class InstructorToolBlock(XBlock):
             block_id = get_block_id(block)
             block_name = get_block_name(block)
             block_type = get_block_type(block)
+            if not block_type == 'pb-choice':
                 eligible = block_type in block_types
                 if eligible:
                     # If this block is a question whose answers we can export,
@@ -196,6 +197,7 @@ class InstructorToolBlock(XBlock):
                     if ancestors and not ancestors[-1]["eligible"]:
                         for ancestor in ancestors:
                             ancestor["eligible"] = True
+
                 new_entry = {
                     "depth": len(ancestors),
                     "id": block_id,
@@ -203,8 +205,7 @@ class InstructorToolBlock(XBlock):
                     "eligible": eligible,
                 }
                 flat_block_tree.append(new_entry)
-            if block.has_children and not block_type == 'pb-mcq' and not \
-               getattr(block, "has_dynamic_children", lambda: False)():
+                if block.has_children and not getattr(block, "has_dynamic_children", lambda: False)():
                     for child_id in block.children:
                         build_tree(block.runtime.get_block(child_id), ancestors=(ancestors + [new_entry]))