Fetches and parses an app manifest from a repository URL, at version when
given (otherwise the default branch).
Injected into the graph builder so it can be unit-tested without network
access. Returns the manifest on success, or an error message when it can't be
retrieved or parsed.
Fetches and parses an app manifest from a repository URL, at
versionwhen given (otherwise the default branch).Injected into the graph builder so it can be unit-tested without network access. Returns the manifest on success, or an error message when it can't be retrieved or parsed.