deltas: skip if projected compressed size does not match text size constraint If we have a delta, we check constraints against a lower bound estimate of the resulting compressed delta. We then checks this projected size against the ?? size constraints. This allows to exclude potential base candidates before doing any expensive computation. This only apply to the intermediate-snapshot case since this constraint only apply to them. For some pathological cases of a private repository this step provide a further performance boost (timing from `hg perfrevlogwrite`): before: 3.145906 seconds after: 3.010646 seconds