Add a stanza constraint too

Author: philderbeast

cabal-install/tests/UnitTests/Distribution/Solver/Modular/Solver.hs

@@ -264,6 +264,11 @@ tests =
             onlyConstrained $
               mkTest db12 "non-goal dependencies are only flag-constrained" ["E", "syb"] $
                 solverFailure (isInfixOf "not a user-provided goal")
+      , runTest $
+          constraints [ExStanzaConstraint (ScopeAnyQualifier "base") [TestStanzas]] $
+            onlyConstrained $
+              mkTest db12 "non-goal dependencies are only stanza-constrained" ["E", "syb"] $
+                solverFailure (isInfixOf "not a user-provided goal")
       , runTest $
           constraints [ExVersionConstraint (ScopeAnyQualifier "base") (V.thisVersion (V.mkVersion [4]))] $
             onlyConstrained $