[pkg-go] Bug#802796: docker-registry: FTBFS: favors unavailable package versions

[Aaron M. Ucko]

Source: docker-registry
Version: 2.1.1~ds1-1
Severity: serious
Justification: fails to build from source

Automated builds of docker-registry have been failing due to the
autobuilders' policy of disregarding alternatives in most cases for
the sake of reproducibility (as in golang-github-vbatts-tar-split bug
#798725):

  The following packages have unmet dependencies:
   sbuild-build-depends-docker-registry-dummy : Depends: golang-github-docker-docker-dev but it is not installable
                                                Depends: golang-golang-x-crypto-dev but it is not installable
                                                Depends: golang-gopkg-check.v1-dev but it is not installable
                                                Depends: golang-gopkg-yaml.v2-dev but it is not installable

Please flip the relevant Build-Depends clauses until packages with the
new names hit unstable.

Thanks!