Undoing created dependency leaves task in modified state

[matsbryntse]

Forum post

An additional somewhat related issue can be seen by creating a link/dependency and then undoing the change.

Go to the undo/redo example here: https://www.bryntum.com/examples/gantt/undoredo/
Create a link between the "Unit tests" task and the "UI unit tests / individual screens"
Undo
In the browser console, run the following

gantt.project.taskStore.changes.modified.map(t => ({ name: t.name, changes: JSON.stringify(t.meta.modified)}))

[pmiklashevych]

Not reproducible in both release and master. Must have been fixed in #975