Comment 2 for bug 237315

I don't think it should be escaped, because a not operator is useful for searches in general, the "-term" syntax is more familiar to anyone who's used Google, and escaping it wouldn't stop exactly the same error from occurring with "!de" anyway.

However, it would make sense to disallow searching with a not operator (regardless of syntax) unless the search string also contains at least one positive term. So <https://launchpad.net/people/?name=-de&searchfor=all> would return an error telling you to add more terms, but <https://launchpad.net/people/?name=foo+-de&searchfor=all> would work.

Further, it probably doesn't make sense to allow not operators in the popup search (hence bug 123898).