Prevent tree log crash if commit missing

app/views/projects/refs/logs_tree.js.haml

 - @logs.each do |content_data|
   - file_name = content_data[:file_name]
   - commit = content_data[:commit]
+  - next unless commit
 
   :plain
     var row = $("table.table_#{@hex_path} tr.file_#{hexdigest(file_name)}");