Where a purchaser of a legal estate is entitled to acquire the same discharged from an equitable interest which is protected by registration as a pending action, annuity, writ, order... or land charge, and which will not be over-reached by the conveyance to him, he may notwithstanding any stipulation to the contrary, require—
that the registration shall be cancelled; or
that the person entitled to the equitable interest shall concur in the conveyance;
and in either case free of expense to the purchaser.
Where the registration cannot be cancelled or the person entitled to the equitable interest refuses to concur in the conveyance, this section does not affect the right of any person to rescind the contract.