The build is unreachable.

Build log

> /tmp/stackage-build2454$ stack unpack natural-transformation-0.4@sha256:f483ea4337b7409290f3e3abe8f00bf26894c622f1dcd0e436b83e534e70b261
Populating index cache ...
Populated index cache.
Unpacked natural-transformation-0.4 to /tmp/stackage-build2454/natural-transformation-0.4/
> /tmp/stackage-build2454/natural-transformation-0.4$ 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/natural-transformation-0.4$ ./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/natural-transformation-0.4 --htmldir=/home/circleci/project/builds/nightly/doc/natural-transformation-0.4 --haddockdir=/home/circleci/project/builds/nightly/doc/natural-transformation-0.4
Configuring natural-transformation-0.4...
> /tmp/stackage-build2454/natural-transformation-0.4$ ghc -clear-package-db -global-package-db -package-db=/home/circleci/project/builds/nightly/pkgdb Setup
> /tmp/stackage-build2454/natural-transformation-0.4$ ./Setup build
Preprocessing library for natural-transformation-0.4..
Building library for natural-transformation-0.4..
[1 of 3] Compiling Control.Natural  ( src/Control/Natural.hs, dist/build/Control/Natural.o )
[2 of 3] Compiling Control.Natural.RULES ( src/Control/Natural/RULES.hs, dist/build/Control/Natural/RULES.o )
[3 of 3] Compiling Control.Object   ( src/Control/Object.hs, dist/build/Control/Object.o )
> /tmp/stackage-build2454/natural-transformation-0.4$ ghc -clear-package-db -global-package-db -package-db=/home/circleci/project/builds/nightly/pkgdb Setup
> /tmp/stackage-build2454/natural-transformation-0.4$ ./Setup copy
Installing library in /home/circleci/project/builds/nightly/lib/x86_64-linux-ghc-8.7.20181117/natural-transformation-0.4-GetNVh5YZQM5wKeIcPYC4h
> /tmp/stackage-build2454/natural-transformation-0.4$ ghc -clear-package-db -global-package-db -package-db=/home/circleci/project/builds/nightly/pkgdb Setup
> /tmp/stackage-build2454/natural-transformation-0.4$ ./Setup register
Registering library for natural-transformation-0.4..