Unclear Duplicate URL key error

### How to recreate:
When a `request_path` in the `url_rewrite` table already exists. Import wil fail with `URL key for specified store already exists.` error. 

### Problem:
This error does not tell on which record the import failed.  Often Import are very large, so it not easy to figure out which is the duplicate

### Sugested solutions:
Skipping failed records and writing the a log

