Custom/Buildpack builders should support glob patterns for dependencies

[dsyer]

Here's the example in the docs:

custom:
  buildCommand: ./build.sh
  dependencies:
    paths:
    - pkg/**
    - src/*.go
    ignore:
    - vendor/**

When I do that I get "... stating file pkg/**: no such file or directory" and skaffold crashes. It works for me with just the directory. Is that expected? If so, maybe it should be reflected in the docs.

[balopat]

Thank you Dave for opening the issue!
We are talking about https://skaffold.dev/docs/pipeline-stages/builders/custom/#paths-and-ignore, right?

Yeah, this is a mistake - dependencies don't support glob patterns yet - but they should - because funnily enough, the same function is used for Dockerfile dependency calculation that is derived from the COPY commands. However glob patterns work there! So, the real issue is that when we implemented the custom builder and the buildpack builder also (!) we missed the glob expansion logic!

I'll rename this bug to reflect the bug. We should support glob patterns in custom/buildpack dependencies.

cc @dgageot