This commit clarifies that the meaning of the `meta.sourceProvenance`
field is independent of and unaffected by the value of the
`meta.license` field. This is based on the intent of the RFC author
as expressed here:
https://github.com/NixOS/nixpkgs/pull/161098#issuecomment-1081270201
This clarification is added for two reasons:
1. If in the future there should be some disagreement about what
`sourceProvenance` to assign to a package, this may help resolve
the disagreement. Any interpretation of `sourceProvenance` which
is influenced by the `meta.license` is clearly an incorrect
interpretation.
2. If it should turn out that it is impossible to disentangle
`sourceProvenance` from `meta.license`, this would indicate the
need for changes to the `sourceProvenance` scheme. That change
might be as simple as replacing the sentence added by this commit
with some other sentence explaining how the two fields influence
each other.
This commit implements the recommendation made in the paragraph of
this comments which begins with "Please say this explicitly...":
https://github.com/NixOS/nixpkgs/pull/161098#issuecomment-1081309089