At http://en.wikipedia.beta.wmflabs.org/wiki/Special:MovePage/Talk:Sentimental
it is impossible to select the checkbox for "Leave a redirect behind".
I believe this is due to how ContentHandler handles 'ContentHandler->supportsRedirects'. A Flow board can not be a redirect, but it's fine to redirect to a Flow board. ContentHandler doesn't understand this.
See also: T102300: Add redirect capability to Flow