The build is unreachable.

Build log

> /tmp/stackage-build2456$ stack unpack loop-0.3.0@sha256:bcc65428e53e9325523fdb80af3c04750548d8ee3f9ad6841272ca679f331bf2
Unpacked loop-0.3.0 to /tmp/stackage-build2456/loop-0.3.0/
> /tmp/stackage-build2456/loop-0.3.0$ 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-build2456/loop-0.3.0$ ./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/loop-0.3.0 --htmldir=/home/circleci/project/builds/nightly/doc/loop-0.3.0 --haddockdir=/home/circleci/project/builds/nightly/doc/loop-0.3.0
Configuring loop-0.3.0...
> /tmp/stackage-build2456/loop-0.3.0$ ghc -clear-package-db -global-package-db -package-db=/home/circleci/project/builds/nightly/pkgdb Setup
> /tmp/stackage-build2456/loop-0.3.0$ ./Setup build
Preprocessing library for loop-0.3.0..
Building library for loop-0.3.0..
[1 of 2] Compiling Control.Loop     ( src/Control/Loop.hs, dist/build/Control/Loop.o )
[2 of 2] Compiling Control.Loop.Internal ( src/Control/Loop/Internal.hs, dist/build/Control/Loop/Internal.o )
> /tmp/stackage-build2456/loop-0.3.0$ ghc -clear-package-db -global-package-db -package-db=/home/circleci/project/builds/nightly/pkgdb Setup
> /tmp/stackage-build2456/loop-0.3.0$ ./Setup copy
Installing library in /home/circleci/project/builds/nightly/lib/x86_64-linux-ghc-8.7.20181117/loop-0.3.0-KBOFzTkURfGITuXz2VUslN
> /tmp/stackage-build2456/loop-0.3.0$ ghc -clear-package-db -global-package-db -package-db=/home/circleci/project/builds/nightly/pkgdb Setup
> /tmp/stackage-build2456/loop-0.3.0$ ./Setup register
Registering library for loop-0.3.0..