parent env can override pantry runtime env

[mxcl]

If the runtime env does not recurse its key, parent env overrides.

Eg. SSL_CERT_FILE={{prefix}}, if the parent env sets SSL_CERT_FILE then it persists.

Most runtime env recurses, eg. PYTHONPATH={{prefix}}/lib/python:$PYTHONPATH, and in such cases the parent env is inserted (this is unchanged behavior).

Fixes #1101

[mxcl]

$ pkgx +curl.se/ca-certs
SSL_CERT_FILE="${SSL_CERT_FILE:-/Users/mxcl/.pkgx/curl.se/ca-certs/v2024.12.31/ssl/cert.pem}"

$ pkgx +curl.se/ca-certs -- env
SSL_CERT_FILE=/Users/mxcl/.pkgx/curl.se/ca-certs/v2024.12.31/ssl/cert.pem

$ SSL_CERT_FILE=foo pkgx +curl.se/ca-certs -- env
SSL_CERT_FILE=foo

$ eval "$(pkgx +curl.se/ca-certs)"
$ echo $SSL_CERT_FILE
/Users/mxcl/.pkgx/curl.se/ca-certs/v2024.12.31/ssl/cert.pem

$ SSL_CERT_FILE=foo
$ eval "$(pkgx +curl.se/ca-certs)"
$ echo $SSL_CERT_FILE
foo

[jhheider]

Hairy, but it doesn't look wrong.

[mxcl]

Yeah I hate using magic strings like this, but I am not fresh enough at 1am Friday to do better.

[mxcl]

More interested in if you think the behavior is right or if I'm missing something.

[coveralls]

coverage: 90.922% (-0.4%) from 91.36%
when pulling 94bc612 on env-overrides
into df7249b on main.

[jhheider]

I think the problem for certain keys is they're not arrayable by default. Most of the ones we set are, but I believe this one isn't. So, you have to decide which values to trust.

[mxcl]

The pantry runtime key decides. If it recurses the key we inherit the env, if not the parent env overrides. For all the keys we set based on directories in the pkgs they are all arrays. This PR is solely about keys from pantry runtime env that don’t recurse.