Make Fake-Cache a bit portable

[matthid]

Description

Currently you cannot move your fake-cache alongside the script without any bad sideeffects.
This issue should be used to investigate where we can automatically invalidate/detect such scenarios and also investigate where we can for example save relative paths to allow copying.

[OlegZee]

@matthid, is it the same case as if I put the build script to folder:

[matthid]

@OlegZee I guess you mean "Moving" the script to a different folder or moving the project?

[OlegZee]

@matthid I just moved the script to a samples folder and now I cannot run it without changing current folder.

[matthid]

Yes we need to allow that. Current workaround is to rm -rf .fake...
Basically I always thought the .fake is not in the working directory but alongside the script (or maybe it is always alongside paket.dependencies, not sure which one is better actually).

[OlegZee]

Btw, do you know FAKE is also affected by an https://github.com/dotnet/cli/issues/4808? Offtopic here but hardly deserve its own issue.

[matthid]

Basically yes, however nobody seems to notice because fake is in the root folder and not a lot of stuff is living there I guess. Or people use chocolatey ;)

[matthid]

I think this is solved by storing relative paths (relative to the script) into the fake cache in addition to detecting the nuget-packages directory. This should cover most cases besides the one you posted @OlegZee . To handle that scenario I think it makes the most sense to detect that error and hint the user into deleting the .fake directory.

[matthid]

or save the .fake directory always alongside the script path (not the working directory)