Feature/duplicate fragments

[acholyn]

closes #393

• Have expanded the current duplication functionality to include tracking of duplicates (similarly to mentions) and alerting users when attempting to edit certain facets of an anonymous/fragment if there are duplicates.
• This functionality is extended to when fragments and anonymous fragments are converted between
• When duplicating an anonymous/fragment the new fragment is added to the duplicates field
• There is a field for anonymous fragments to be used when a conversion has happened
• they have a property called duplicates_list which combines duplicates from the property and the reverse relationships

[tcouch]

A couple of things still to do:

• Duplicating a duplicate should make the new fragment a duplicate of both the original and the first duplicate.
• Users should see a warning that a fragment has duplicates if they try to edit it. Maybe a banner at the top?

[acholyn]

would it work in that when duplicating, if the original has duplicates, add those items to the new instance's list of duplicates and it to theirs?

[tcouch]

I get an error when converting an anonymous fragment with duplicates into an unlinked fragment. To reproduce:

1. Duplicate an anonymous fragment
2. Convert the original anonymous fragment to unlinked

Result:

ValueError: Cannot query "Unlinked 450": Must be "AnonymousFragment" instance.

[tcouch]

Did we raise the issue of what to do about testimonia? I can see there's no option to duplicate testimonia on the detail page, but wasn't sure if we'd asked about this?

If it's not an option, these fields are redundant, but I guess not causing any harm. Maybe just add a comment here and in models/base.py to state that these are here and why if that's the case.

[acholyn]

I'm not sure we did ask if we should enable it for them, I'll make note to do that. They are currently redundant but are there because it's on the HistoricalBaseModel and it complained when I removed this from the migration.

[acholyn]

conversion issue should be fixed now but initially the new fragment page didn't load and I had to reload for it to display, wondering if this was specific to my device

[tcouch]

I think the migration leaf node error we're seeing is because GH actions actually runs some kind of merged version of this branch and development together. Usually it's quite good at telling you there's a conflict, but in the case of migrations it's not clever enough to warn that development has a 0070 migration file and so does this branch.

TL;DR: Merge development into this branch and resolve the migration conflict by making this branch's migration file 0071.