Yes the latest change that checked for the correctly mounted directory before deleting the mysql database has been merged, and is available in both stable and master branches.
That said the above issue by @kazak shows the script exiting at the point where it cannot find the mysql database.
It looks like there are multiple drives connected.
@kazak @ear9mrn do you both have multiple drives connected? Can you do the initial USB import process with only the old SD card in a single USB drive connected and then after completion connect the second?