- vendor in hex_core at v0.5.0
  - Change where repo_name should be the org and not the parent
  - Changed rebar_utils:url_append_path/2 to not explicitly add a '?',
    this is returned in the Query chunk by http_uri:parse/1 (e.g., "?foo=bar")
  - update organization_merging test to expect the sub-repo as the repo_name
  - Add tests for rebar_utils:url_append_path/2
  - Stop referencing/setting "organization" in config and use new
     organization settings (api_repository and repo_organization)
  - Do not set (assume) the read key is valid for any/every repo
  - Set repo_organization and api_repository to org
  - Update tests to check for new config opts

When a given behaviour module does not exist, rebar3 brutally crashes.
This patch makes it so instead, there is a warning output menitoning the
missing behaviour, and this one is omitted from the unused function
calls check. This means that unused calls will instead be shown for the
module implementing a non-existing behaviour, as if no behaviour were
declared in the first place.

pr2relnotes takes merged PRs from the git log and generates
formatted release notes including links to the PRs themselves