prepend path for build

[wolfv]

cc @beckermr

[beckermr]

This is not a full fix since in the build environment CONDA_PREFIX will still not be the same as PREFIX.

[beckermr]

We need to also not make the build env at all.

[wolfv]

Hey @beckermr sorry for just doing it - I would have loved your contribution but it is a little bit in the weeds of things. But maybe it can help you get kick-started into rattler-build development anyways :)

If you want to try this locally, I use:

cargo r -- build --recipe ./examples/...

I had a test recipe that looked like this:

package:
  name: foobar
  version: 1.0.0

build:
  merge_build_and_host_envs: true
  script:
    - echo "foo"
    - exit 22
requirements:
  build:
    - ${{ compiler('c') }}
  host:
    - zlib

[beckermr]

Ah great for the tips and no problem on just doing. I appreciate the fix!