What is an obligation of a search warrant holder to notify the issuing magistrate of a change in circumstance prior to a search?

"Prior to a search there is an obligation to bring to the attention of an issuing magistrate any change of circumstance based upon additional or corrective information known to government agents, if the new information could reasonably have affected the judicial officer's decision had it been made known to him before issuance of the warrant." United States v. Morales, 568 F. Supp. 646, 649 (E.D.N.Y. 1983). For example, in U.S. v. Bowling, 900 F.2d 926 (6th Cir. 1990), while one group of officers was obtaining a warrant, a second group was waiting outside the defendants' home. At some point, defendants consented to a search by the second group of officers, which was performed hastily and revealed nothing incriminating. When the first group of officers later arrived with the search warrant, the second group informed them about the unsuccessful search. The officers then executed the warrant without first disclosing to the magistrate that an initial search had already been conducted.