Building cabal-helper-0.8.1.2 with Stack failed with 'Dependency cycle detected' error. It seems to be https://github.com/commercialhaskell/stack/issues/4265 Stack bug. As a temporary solution I added source code of cabal-helper package to vendor directory and commented out 'build-tool-depends: cabal-helper:cabal-helper-wrapper' line in the cabal-helper.cabal file.
