* Bring forward push of the version tag ref so it happens alongside
the push of the suite branch ref.
* Include canonicalised suite name in signed tag message.
+ * Mention cross-version dgit rpush incompatibility in manpage.
* New git-check and git-create methods "true" which are no-ops.
* test-dummy-drs `distro': for testing dgit-repos-server. WIP.