plan execution fails to build computed dependency

This currently affects the `2.0` and `master` branch

I've create a reasonably minimal repro-case over at https://github.com/hvr/cabal-bugs/tree/master/issue-4432 (the `rm -rf` part is probably not necessary for reproducing this) . You can see the problem below; I suspect that this may be a corner case involving a local `Cabal` library.

```
$ cabal new-build -j1
Resolving dependencies...
In order, the following will be built (use -v for more details):
- Cabal-1.25.0.0 (lib) (first run)
- base-orphans-0.5.4 (lib) (requires build)
- transformers-compat-0.5.1.4 (lib) (requires build)
- cabal-doctest-1 (lib) (requires build)
- tagged-0.8.5 (lib) (requires build)
- distributive-0.5.2 (lib:distributive) (requires build)
- bug-0 (lib) (first run)
Configuring library for Cabal-1.25.0.0..
Preprocessing library for Cabal-1.25.0.0..
Building library for Cabal-1.25.0.0..
Configuring library for base-orphans-0.5.4..
Preprocessing library for base-orphans-0.5.4..
Building library for base-orphans-0.5.4..
[1 of 2] Compiling Data.Orphans.Prelude ( src/Data/Orphans/Prelude.hs, dist/build/Data/Orphans/Prelude.o )
[2 of 2] Compiling Data.Orphans ( src/Data/Orphans.hs, dist/build/Data/Orphans.o )
Installing library in /home/hvr/.cabal/store/ghc-8.0.2/base-orphans-0.5.4-982467a5ac7bbf2cffaf0aa75d70cd89144cf8ad3d49ec14dcbc91afa87fc464/lib
Configuring library for transformers-compat-0.5.1.4..
Preprocessing library for transformers-compat-0.5.1.4..
Building library for transformers-compat-0.5.1.4..
[1 of 2] Compiling Paths_transformers_compat ( dist/build/autogen/Paths_transformers_compat.hs, dist/build/Paths_transformers_compat.o )
[2 of 2] Compiling Control.Monad.Trans.Instances ( src/Control/Monad/Trans/Instances.hs, dist/build/Control/Monad/Trans/Instances.o )
Installing library in /home/hvr/.cabal/store/ghc-8.0.2/transformers-compat-0.5.1.4-8e1d956321b8695a2a214c4cc483605a5e92f9d86a100c8e03261cf4ec11e097/lib
Configuring library for cabal-doctest-1..
Configuring library for tagged-0.8.5..
Preprocessing library for tagged-0.8.5..
Building library for tagged-0.8.5..
[1 of 2] Compiling Data.Tagged ( src/Data/Tagged.hs, dist/build/Data/Tagged.o )
[2 of 2] Compiling Data.Proxy.TH ( src/Data/Proxy/TH.hs, dist/build/Data/Proxy/TH.o )
Installing library in /home/hvr/.cabal/store/ghc-8.0.2/tagged-0.8.5-609d13fa0a84ebb0b1b526949ac135749ded6381301a67420b356ef9adb9a5c7/lib
: cannot satisfy -package-id cabal-doctest-1-inplace
(use -v for more information)
cabal: Failed to build distributive-0.5.2 (which is required by bug-0). The
failure occurred during the configure step.
```

And here's the dep-tree (pretty-printed by `cabal-plan`):

```
bug-0
├─ Cabal-1.25.0.0
│ ├─ array-0.5.1.1
│ │ └─ base-4.9.1.0
│ │ ├─ ghc-prim-0.5.0.0
│ │ │ └─ rts-1.0
│ │ ├─ integer-gmp-1.0.0.1
│ │ │ └─ ghc-prim-0.5.0.0 ┄┄
│ │ └─ rts-1.0 ┄┄
│ ├─ base-4.9.1.0 ┄┄
│ ├─ binary-0.8.3.0
│ │ ├─ array-0.5.1.1 ┄┄
│ │ ├─ base-4.9.1.0 ┄┄
│ │ ├─ bytestring-0.10.8.1
│ │ │ ├─ base-4.9.1.0 ┄┄
│ │ │ ├─ deepseq-1.4.2.0
│ │ │ │ ├─ array-0.5.1.1 ┄┄
│ │ │ │ └─ base-4.9.1.0 ┄┄
│ │ │ ├─ ghc-prim-0.5.0.0 ┄┄
│ │ │ └─ integer-gmp-1.0.0.1 ┄┄
│ │ └─ containers-0.5.7.1
│ │ ├─ array-0.5.1.1 ┄┄
│ │ ├─ base-4.9.1.0 ┄┄
│ │ ├─ deepseq-1.4.2.0 ┄┄
│ │ └─ ghc-prim-0.5.0.0 ┄┄
│ ├─ bytestring-0.10.8.1 ┄┄
│ ├─ containers-0.5.7.1 ┄┄
│ ├─ deepseq-1.4.2.0 ┄┄
│ ├─ directory-1.3.0.0
│ │ ├─ base-4.9.1.0 ┄┄
│ │ ├─ filepath-1.4.1.1
│ │ │ └─ base-4.9.1.0 ┄┄
│ │ ├─ time-1.6.0.1
│ │ │ ├─ base-4.9.1.0 ┄┄
│ │ │ └─ deepseq-1.4.2.0 ┄┄
│ │ └─ unix-2.7.2.1
│ │ ├─ base-4.9.1.0 ┄┄
│ │ ├─ bytestring-0.10.8.1 ┄┄
│ │ └─ time-1.6.0.1 ┄┄
│ ├─ filepath-1.4.1.1 ┄┄
│ ├─ pretty-1.1.3.3
│ │ ├─ base-4.9.1.0 ┄┄
│ │ ├─ deepseq-1.4.2.0 ┄┄
│ │ └─ ghc-prim-0.5.0.0 ┄┄
│ ├─ process-1.4.3.0
│ │ ├─ base-4.9.1.0 ┄┄
│ │ ├─ deepseq-1.4.2.0 ┄┄
│ │ ├─ directory-1.3.0.0 ┄┄
│ │ ├─ filepath-1.4.1.1 ┄┄
│ │ └─ unix-2.7.2.1 ┄┄
│ ├─ time-1.6.0.1 ┄┄
│ └─ unix-2.7.2.1 ┄┄
├─ base-4.9.1.0 ┄┄
└─ distributive-0.5.2
├─ base-4.9.1.0 ┄┄
├─ base-orphans-0.5.4
│ ├─ base-4.9.1.0 ┄┄
│ └─ ghc-prim-0.5.0.0 ┄┄
├─ tagged-0.8.5
│ ├─ base-4.9.1.0 ┄┄
│ ├─ deepseq-1.4.2.0 ┄┄
│ ├─ template-haskell-2.11.1.0
│ │ ├─ base-4.9.1.0 ┄┄
│ │ ├─ ghc-boot-th-8.0.2
│ │ │ └─ base-4.9.1.0 ┄┄
│ │ └─ pretty-1.1.3.3 ┄┄
│ ├─ transformers-0.5.2.0
│ │ └─ base-4.9.1.0 ┄┄
│ └─ transformers-compat-0.5.1.4
│ ├─ base-4.9.1.0 ┄┄
│ ├─ ghc-prim-0.5.0.0 ┄┄
│ └─ transformers-0.5.2.0 ┄┄
├─ transformers-0.5.2.0 ┄┄
└─ transformers-compat-0.5.1.4 ┄┄
[setup]
├─ Cabal-1.25.0.0 ┄┄
├─ base-4.9.1.0 ┄┄
└─ cabal-doctest-1
├─ Cabal-1.25.0.0 ┄┄
├─ base-4.9.1.0 ┄┄
├─ directory-1.3.0.0 ┄┄
└─ filepath-1.4.1.1 ┄┄
```