Keep Non Auto-mapped Fields if a User Returns to Step 1:Scan & Upload CSV file to reupload the CSV file

A user tries to import a CSV file using a saved import mapping when he realizes that he needs to re-upload the file for some reason. He's at the point where he's done with the mapping where some fields are auto-mapped as part of the saved mapping and the rest where manually mapped by the user. If he goes back to 
Step 1:Scan & Upload CSV file, he loses the mapping of those he did manually. This is intentional and the workaround is to save the mappings first by clicking Next in the Field Mapping page before going back to previous pages. Note also that changes on the previous 2 pages can change the mapping possibilities.