I ran into an issue where when I upgraded the migration script would fail with built in packages. It would fail to move files, restart and then try to move all the files again which caused some weird behavior
2019-01-29 12:27:19.3552 900 7 INFO Moving the existing built in packages feed into the Default space
2019-01-29 12:27:19.3922 900 7 INFO The destination D:/Octopus/Packages\Spaces-1\feeds-builtin already exists, probably because this migration has been attempted before. Attempting to move the individual files and sub directories instead. This might take a bit longer.
2019-01-29 12:27:19.3922 900 7 INFO Moving subdirectories and files from D:\Octopus\PackagesTemp to D:/Octopus/Packages\Spaces-1\feeds-builtin
2019-01-29 12:27:19.3922 900 7 INFO Moving subdirectory D:\Octopus\PackagesTemp\Cvent.Octo.Integration to D:/Octopus/Packages\Spaces-1\feeds-builtin\Cvent.Octo.Integration
2019-01-29 12:27:19.3922 900 7 INFO Moved failed, attempting to copy D:\Octopus\PackagesTemp\Cvent.Octo.Integration to D:/Octopus/Packages\Spaces-1\feeds-builtin\Cvent.Octo.Integration recursively instead.
2019-01-29 12:27:19.5042 900 7 INFO Moving subdirectories and files from D:/Octopus/Packages to D:/Octopus/Packages\Spaces-1\feeds-builtin
2019-01-29 12:27:19.5042 900 7 INFO Moving subdirectory D:/Octopus/Packages\Spaces-1 to D:/Octopus/Packages\Spaces-1\feeds-builtin\Spaces-1
2019-01-29 12:27:19.5042 900 7 INFO Moved failed, attempting to copy D:/Octopus/Packages\Spaces-1 to D:/Octopus/Packages\Spaces-1\feeds-builtin\Spaces-1 recursively instead.
This caused it to make some weird folder structures