With latest --git version, neither --force-dirty nor --coverage rebuilds anything.

### Steps to reproduce

My yaml file is at https://gist.github.com/anonymous/bc558eb672c7b1dee0736f1349c9bdbf

Version is: Version 1.5.1, Git revision 356fc5a35c2e87a4d3b9c4180452acd18e0b4b00 x86_64 hpack-0.17.1

Repro is just that "stack build --force-dirty hblog" and "stack build --coverage hblog" do not recompile any of the executables, but "echo ' ' >>app/hblog.hs" followed by stack build does do so.

### Expected

Rebuilds for both --force-dirty and --coverage.

### Actual

Here's a non-verbose example with --coverage:

```
rlpowell@e8162885bd95> stack build --coverage hblog
hblog-0.1.0.0: unregistering (flags changed from [] to ["--ghc-options","-fhpc"])
hblog-0.1.0.0: configure (lib + exe)
Configuring hblog-0.1.0.0...
hblog-0.1.0.0: build (lib + exe)
Preprocessing library hblog-0.1.0.0...
Preprocessing executable 'hblog' for hblog-0.1.0.0...
Preprocessing executable 'rectifier' for hblog-0.1.0.0...
Preprocessing executable 'tiki_to_md' for hblog-0.1.0.0...
Preprocessing executable 'unphone' for hblog-0.1.0.0...
hblog-0.1.0.0: copy/register
Installing library in
/home/rlpowell/src/hblog/.stack-work/install/x86_64-linux/lts-8.16/8.0.2/lib/x86_64-linux-ghc-8.0.2/hblog-0.1.0.0-7cALF3ewsIBLsLx7HTEy4X
Installing executable(s) in
/home/rlpowell/src/hblog/.stack-work/install/x86_64-linux/lts-8.16/8.0.2/bin
Registering hblog-0.1.0.0...
No tix files found in /home/rlpowell/src/hblog/.stack-work/install/x86_64-linux/lts-8.16/8.0.2/hpc/, so not generating a unified coverage report.
```

Various --verbose examples are at https://gist.github.com/anonymous/7508edb28c1c691951c73bc802504bf3 ; note in particular that when I append a new space to one of the source files, that executable *does* get rebuilt.

### Stack version

```
$ stack --version
Version 1.5.0, Git revision 63267f94d7c819cbecc2d59aa259d17240838e43 (4845 commits) x86_64 hpack-0.17.1
```

### Method of installation

stack upgrade --git , a few hours ago.