A customer who needs to restrict a branch to the role developer. They edit the role under security settings with their admin user, such as:
 
> 1. Log in as admin user to the UI;
> 2. Navigate to Admin -> Security -> Roles -> developer;
> 3. On the right side of the screen that shows Permissions for the developer role click on the arrow next to the Project;
> 4. Click on "add exception" link and select the project that the user is going to work on;
> 5. Allow "Read" permission but disable "Update";
> 6. Save this change.

The same thing, they have given the contributor role to developers to that project and such role doesn't have writer permission on the restricted branch.
 
Once you have this complete, you would not see the save button but you'll still be able to upload the spreadsheet.
 
NOTE: The above is happening as well on RHDM in all versions