Is a plaintiff entitled to counsel fees even if the court declines to enter judgment on that claim?

[when] a plaintiff joins a claim under one of the statutes enumerated in [section 1988, for which attorney's fees are available,] with a claim that does not allow attorney fees, that plaintiff, if it prevails on the non-fee claim, is entitled to a determination on the other claim for the purpose of awarding counsel fees. In some instances, however, the claim with fees may involve a constitutional question which the courts are reluctant to resolve if the non-constitutional claim is dispositive. In such cases, if the claim for which fees may be awarded meets the "substantiality" test [enunciated in] Hagans v. Lavine [, 415 U.S. 528, 94 S.Ct. 1372, 39 L.Ed.2d 577 (1974),] attorney's fees may be allowed even though the court declines to enter judgment for the plaintiff on that claim, so long as the plaintiff prevails on the non-fee claim arising out of a "common nucleus of operative fact."