Regression in v0.9: entrypoint binary is not on PATH

[imjasonh]

ko v0.8.0:

$ crane config $(go run ./ publish ./test) | jq .config.Env
[
  "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/ko-app",
  "SSL_CERT_FILE=/etc/ssl/certs/ca-certificates.crt",
  "KO_DATA_PATH=/var/run/ko"
]

ko v0.9.1:

$ crane config $(go run ./ publish ./test) | jq .config.Env
[
  "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/ko-app/test",
  "SSL_CERT_FILE=/etc/ssl/certs/ca-certificates.crt",
  "KO_DATA_PATH=/var/run/ko"
]

This is likely caused by changes to PATH to support Windows.

This change in behavior causes users that call ko-built images with the binary name as the command, without /ko-app/ prefix, to fail.

This probably warrants a v0.9.2.

[imjasonh]

Yep: https://github.com/google/ko/pull/374/files#diff-ec8e4ed8cdc5703f7558043358223fb0cd6656105f78be8d576ec0f7b5362217R461

https://github.com/google/ko/blob/5a8663b58dfeb5db05df0a10496bd618e52d51fd/pkg/build/gobuild_test.go#L539

This should be /ko-app, not /ko-app/test.