The build is unreachable.

Build log

> /tmp/stackage-build2454$ stack unpack Decimal-0.5.1@sha256:06bdd0f8badfb2104fd052f64888c283792a08f9a0d3661339e133e073080299
Unpacked Decimal-0.5.1 to /tmp/stackage-build2454/Decimal-0.5.1/
> /tmp/stackage-build2454/Decimal-0.5.1$ 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-build2454/Decimal-0.5.1$ ./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/Decimal-0.5.1 --htmldir=/home/circleci/project/builds/nightly/doc/Decimal-0.5.1 --haddockdir=/home/circleci/project/builds/nightly/doc/Decimal-0.5.1
Configuring Decimal-0.5.1...
> /tmp/stackage-build2454/Decimal-0.5.1$ ghc -clear-package-db -global-package-db -package-db=/home/circleci/project/builds/nightly/pkgdb Setup
> /tmp/stackage-build2454/Decimal-0.5.1$ ./Setup build
Preprocessing library for Decimal-0.5.1..
Building library for Decimal-0.5.1..
[1 of 1] Compiling Data.Decimal     ( src/Data/Decimal.hs, dist/build/Data/Decimal.o )
> /tmp/stackage-build2454/Decimal-0.5.1$ ghc -clear-package-db -global-package-db -package-db=/home/circleci/project/builds/nightly/pkgdb Setup
> /tmp/stackage-build2454/Decimal-0.5.1$ ./Setup copy
Installing library in /home/circleci/project/builds/nightly/lib/x86_64-linux-ghc-8.7.20181117/Decimal-0.5.1-Dlj8tsawcugHwOaxSTfZEt
> /tmp/stackage-build2454/Decimal-0.5.1$ ghc -clear-package-db -global-package-db -package-db=/home/circleci/project/builds/nightly/pkgdb Setup
> /tmp/stackage-build2454/Decimal-0.5.1$ ./Setup register
Registering library for Decimal-0.5.1..