precheck XOR includes lowtap density areaid

[jeffdi]

There is a tap low density area in the user project area. Caused the fom fill to space out? (Marwan during the 2404/6 post mortem).

[d-m-bailey]

This may be due to a mismatch in the cell boundary size, reflecting a real difference.

If that is the case, it would be a true problem and this issue should be closed.