The build is unreachable.

Build log

> /tmp/stackage-build2451$ stack unpack string-conversions-0.4.0.1@sha256:9c4075e54aa6cabfe244e07e2a1de720f3e98a0a6980fc671ab9c0da30f0f259
Unpacked string-conversions-0.4.0.1 to /tmp/stackage-build2451/string-conversions-0.4.0.1/
> /tmp/stackage-build2451/string-conversions-0.4.0.1$ ghc -clear-package-db -global-package-db -package-db=/home/circleci/project/builds/nightly/pkgdb Setup
[1 of 1] Compiling Main             ( Setup.hs, Setup.o )
Linking Setup ...
> /tmp/stackage-build2451/string-conversions-0.4.0.1$ ./Setup configure --package-db=clear --package-db=global --package-db=/home/circleci/project/builds/nightly/pkgdb --libdir=/home/circleci/project/builds/nightly/lib --bindir=/home/circleci/project/builds/nightly/bin --datadir=/home/circleci/project/builds/nightly/share --libexecdir=/home/circleci/project/builds/nightly/libexec --sysconfdir=/home/circleci/project/builds/nightly/etc --docdir=/home/circleci/project/builds/nightly/doc/string-conversions-0.4.0.1 --htmldir=/home/circleci/project/builds/nightly/doc/string-conversions-0.4.0.1 --haddockdir=/home/circleci/project/builds/nightly/doc/string-conversions-0.4.0.1
Configuring string-conversions-0.4.0.1...
> /tmp/stackage-build2451/string-conversions-0.4.0.1$ ghc -clear-package-db -global-package-db -package-db=/home/circleci/project/builds/nightly/pkgdb Setup
> /tmp/stackage-build2451/string-conversions-0.4.0.1$ ./Setup build
Preprocessing library for string-conversions-0.4.0.1..
Building library for string-conversions-0.4.0.1..
[1 of 2] Compiling Data.String.Conversions ( src/Data/String/Conversions.hs, dist/build/Data/String/Conversions.o )

src/Data/String/Conversions.hs:39:1: warning: [-Wunused-imports]
    The import of ‘Data.Monoid’ is redundant
      except perhaps to import instances from ‘Data.Monoid’
    To import instances alone, use: import Data.Monoid()
   |
39 | import Data.Monoid
   | ^^^^^^^^^^^^^^^^^^
[2 of 2] Compiling Data.String.Conversions.Monomorphic ( src/Data/String/Conversions/Monomorphic.hs, dist/build/Data/String/Conversions/Monomorphic.o )
> /tmp/stackage-build2451/string-conversions-0.4.0.1$ ghc -clear-package-db -global-package-db -package-db=/home/circleci/project/builds/nightly/pkgdb Setup
> /tmp/stackage-build2451/string-conversions-0.4.0.1$ ./Setup copy
Installing library in /home/circleci/project/builds/nightly/lib/x86_64-linux-ghc-8.7.20181119/string-conversions-0.4.0.1-3XyYOPozuNz9QIeJ6jagJf
> /tmp/stackage-build2451/string-conversions-0.4.0.1$ ghc -clear-package-db -global-package-db -package-db=/home/circleci/project/builds/nightly/pkgdb Setup
> /tmp/stackage-build2451/string-conversions-0.4.0.1$ ./Setup register
Registering library for string-conversions-0.4.0.1..