Adapted corrections and conflicting deletions should be marked

[divec]

Steps to reproduce:

• Translate nl->en using Google
• In the Dutch, write two paragraphs "Heb je een appel?" and "Eet je een appel?"
• Observer the English candidates are "Do you have an apple?" and "Do you eat an apple?"
• Correct "Do you have an apple?" to "Have you an apple?" and commit.
• Then change "Heb je een appel?" to "Eet je een appel?"

Observed behaviour: The candidate looks like "Have you eat an apple?"
Expected behaviour: Some sort conflict is signalled. The corrected word "Have" is marked somehow.

This is because the English correction diffs as "{-Do-}{+Have+} you{- have-} an apple?", and the two replacement ranges are treated separately to diff3. The "{- have-}" conflicts with the translation update, but the conflict is unrendered because it's a zero-length strike through. The {-Do-}{+Have+} is nonconflicting.

[divec]

Ameliorated by f778eb1 . But if a human pure removal conflicts
with a machine translation replacement, it may still not be obvious there is a conflict (because of the zero-length strikethrough problem)