* guix/import/opam.scm (group-pat): Report in syntax tree.
(dependency->input, dependency->native-input, dependency->name):
consider the case of a group.
* guix/git.scm (update-cached-checkout): Add #:starting-commit
parameter. Call 'commit-relation' when #:starting-commit is true.
Always return the relation or #f as the third value.
(latest-repository-commit): Adjust accordingly.
* guix/import/opam.scm (get-opam-repository): Likewise.
* tests/channels.scm ("latest-channel-instances includes channel dependencies")
("latest-channel-instances excludes duplicate channel dependencies"):
Update mock of 'update-cached-checkout' accordingly.
* guix/import/opam.scm (string-pat, multiline-string, list-pat)
(dict, condition): Export.
(opam-fetch): Add optional 'repository' parameter.
(opam->guix-package): Add #:repository parameter and pass it to
'opam-fetch'.
* tests/opam.scm ("opam->guix-package"): Remove use of 'mock' and pass
TEST-REPO to 'opam->guix-package' instead.
("parse-strings", "parse-multiline-strings")
("parse-lists", "parse-dicts", "parse-conditions"): Remove uses of '@@',
which are no longer needed.
janestreet reversionned its packages and prefixed them with "v". Let the
importer know about that and choose "v" versions first.
* guix/import/opam.scm (find-latest-version): Work around version
rewrite from janestreet.
(opam->guix-package): Do not pass "v" to version number.
