src/__init__.py: class Archive: fix _add_treeitem() in rebased implem…

…entation.

Used to rely on non-existent JM_last_tree(), but now implemented more simply
without it.

src/__init__.py

@@ -1601,15 +1601,10 @@ def _add_dir( self, folder, path=None):
         mupdf.fz_mount_multi_archive( self.this, sub, path)
 
     def _add_treeitem( self, memory, name, path=None):
-        drop_sub = False
         buff = JM_BufferFromBytes( memory)
-        sub = JM_last_tree( self.this, path)
-        if not sub:
-            sub = mupdf.fz_new_tree_archive( None)
-            drop_sub = True
+        sub = mupdf.fz_new_tree_archive( mupdf.FzTree())
         mupdf.fz_tree_archive_add_buffer( sub, name, buff)
-        if drop_sub:
-            mupdf.fz_mount_multi_archive( self.this, sub, path)
+        mupdf.fz_mount_multi_archive( self.this, sub, path)
 
     def _add_ziptarfile( self, filepath, type_, path=None):
         if type_ == 1:
@@ -16203,13 +16198,6 @@ def JM_is_jbig2_image(dict_):
     #        return 1;
     #return 0;
 
-def JM_last_tree(arch, mount):
-    '''
-    Return last archive if it is a tree and mount points match
-    '''
-    assert 0, 'Not implemented'
-
-
 def JM_listbox_value( annot):
     '''
     ListBox retrieve value