Revert "Fix TruncatedBlockGSStep localExactSolve."

This reverts commit b6475d8e.

dune/solvers/iterationsteps/truncatedblockgsstep.hh

@@ -301,9 +301,8 @@ public:
                 typename MBlock::row_type::Iterator inner_it = A[i].begin();
                 typename MBlock::row_type::Iterator inner_end = A[i].end();
                 for(; inner_it!=inner_end; ++inner_it)
-                    if (ignore[i] && inner_it.index()==i)
+                    if (inner_it.index()==i and *inner_it==0.0)
                     {
-                        assert(*inner_it == 0.0);
                         *inner_it = 1.0;
                         b[i] = x[i];
                     }