In the event that title to a unit is transferred by sheriff's sale pursuant to execution upon any lien against the unit, the council may give notice in writing to the sheriff of any unpaid assessments for common expenses which are a charge against the unit, but have not been reduced to lien pursuant to § 2234 of this title, and the sheriff shall pay the assessments of which the sheriff has such notice out of any proceeds of the sale which remain in the sheriff's hands for distribution after payment of all other claims, which the sheriff is required by law to pay, but prior to any distribution of the balance to the former unit owner against whom the execution issued. The purchaser at such sheriff's sale and the unit involved shall not be liable for unpaid assessments for common expenses which became due prior to the sheriff's sale of the unit. Any such unpaid assessments which cannot be promptly collected from the former unit owner may be reassessed by the council as a common expense to be collected from all of the unit owners including such purchaser, the purchaser's heirs, personal representatives, successors and assigns. To protect its right to collect unpaid assessments which are a charge against a unit, the council may, on behalf of the unit owners, purchase the unit at sheriff's sale, provided such action is authorized by the affirmative vote of a majority of the members of council and, if it does so purchase, the council shall thereafter have the power to hold, sell, convey, mortgage or lease such unit to any person whatsoever.