`nimble test` fails due to dirty nimcache, -f needed sometimes
git rev-parse HEAD
1e086d59595c24ee8ec3f1dcc02b55d97fe9e2ec

nimble installWithDeps
nimble test

```
Hint:  [Link]
Undefined symbols for architecture x86_64:
  "__test_call_param_", referenced from:
      _NimMainModule in nimterop_tnimterop_c.c.o
  "_test_call_param2", referenced from:
      _NimMainModule in nimterop_tnimterop_c.c.o
  "_test_call_param3", referenced from:
      _NimMainModule in nimterop_tnimterop_c.c.o
  "_test_call_param4", referenced from:
      _NimMainModule in nimterop_tnimterop_c.c.o
  "_test_call_param5", referenced from:
      _NimMainModule in nimterop_tnimterop_c.c.o
  "_test_call_param6", referenced from:
      _NimMainModule in nimterop_tnimterop_c.c.o
  "_test_call_param7", referenced from:
      _NimMainModule in nimterop_tnimterop_c.c.o
  "_test_call_param8", referenced from:
      _NimMainModule in nimterop_tnimterop_c.c.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Error: execution of an external program failed: 'g++   -o /Users/timothee/git_clone/nim/nimterop/tests/tnimterop_c  /Users/timothee/.cache/nim/tnimterop_c_d/runtime.c.o /Users/timothee/.cache/ni...
```


EDIT: using `-f` to force rebuild worked:
```
nim c -r -f tests/tnimterop_c.nim
```
(so may be hard to reproduce...)

is that a nim bug where nim should recompile because something changed, but didn't recompile?