I'm not sure I see the big deal about this? If we're putting people in a jail cell, even if it's only over night or something, shouldn't the correctional officers (or whatever the equivalent is) at the jail have the discretion to ensure that whoever is going in is not carrying with them a weapon, drugs, etc. ?
Metal detectors and thorough pat-downs already do a pretty good job of ensuring that contraband doesn't enter jails. Also, the Supreme Court has previously ruled that even convicted prisoners (let alone pretrial detainees) still have a Constitutional right to privacy, although limited when security demands do reasonably outweight and override the privacy violations that occur.
I think that one's right to privacy, insofar as it extends to not being forced to display the underside of your genitals or stretch open your anus for the observing corrections officers (which is all actually part of the procedure in question) is more important than the security concern that inmates who have already "passed" several security checks and have earned no individual suspicion still have to be strip searched, "just in case." The fact that even someone arrested wrongfully (or, for that matter, even someone arrested for a minor non-violent offense that only warrants a single night in jail) has to go through such a search just makes it all the more egregious.
When that happens in Germany, police are supposed to call the court in question to verify before proceeding. This has happened to a friend of mine twice (over the same retracted warrant). The first time it happened, I was with him.
Whether they actually do that right away might depend on the circumstances of the arrest / id check / whatever it was and how credible you sound in telling them, obviously.
I don't know the standard practice for something like this, but there was no such discretion in this case, ftr. Mr. Florence always carried with him the documentation that showed his warrant had been expunged, just to be on the safe side. The arresting officer ignored his explanations and also disregarded his wife when she showed him the documents. He was arrested and placed in the jail of Burlington County, NJ until officers from Essex County, NJ (where the bad warrant was from) could arrive to resolve his status. He was strip-searched at the Burlington jail, was detained for a week until Essex County officers finally arrived, transferred to the Essex jail, was strip-searched again there, and was then promptly taken to the Essex County Courthouse where the judge ordered his immediate release. Honestly, a bit of a horror story.