Fix build scripts

make-nix-release.sh

@@ -3,7 +3,7 @@
 set -e
 
 test -n "$PYTHON" || PYTHON="python3"
-$PYTHON get-poetry.py -y
+$PYTHON get-poetry.py -y --preview
 $PYTHON $HOME/.poetry/bin/poetry config virtualenvs.create false
 $PYTHON $HOME/.poetry/bin/poetry install --no-dev
 $PYTHON $HOME/.poetry/bin/poetry run python sonnet make release \

sonnet

@@ -110,8 +110,8 @@ class MakeReleaseCommand(Command):
                     ).stdout
                 )
                 env = VirtualEnv(Path(prefix.strip()), base=Path(prefix.strip()))
-                with package.with_python_versions("~{}".format(version)):
                 solver = Solver(package, pool, Repository(), Repository(), self.io)
+                with solver.use_environment(env):
                     ops = solver.solve()
                     for op in ops:
                         if not env.is_valid_for_marker(op.package.marker):