[pkg-go] Bug#982931: consul FTBFS in some environments.

[Peter Green]

Package: consul
Version: 1.8.7+dfsg1-1
Tags: FTBFS

(not filing as rc because none of the build failures I noticed were on official debian buildds)

I noticed that consul was failing to build in raspbian bullseye with a testsuite failure. So I tried to do a build locally
with the testsuite disabled. That however failed with "Failed to generate outputs from proto/pbcommon/common_oss.proto"

I then did some poking around on reproducible-builds.org and found that there seemed to be problems happening
over there too, but there didn't seem to be much of a consistent pattern :(

sid-amd64: success
bullseye-amd64: first build successful, but second build failed with testsuite failure
sid-i386: first build successful, second build fails to generate outputs from common.proto
bullseye-i386: first build successful, second build fails to generate outputs from common.proto
sid-arm64: first build fails with testsuite failure, second build not tried
bullseye-arm64: success.
sid-armhf: Failed to generate outputs from proto/pbacl/acl.proto
bullseye-armhf: Failed to generate outputs from proto/pbcommon/common.proto

Doing some poking around in the scripts the cause of the failure seems to be
$(go list -f '{{ .Dir }}' -m github.com/gogo/protobuf) evaluating as an empty
string, but i'm at a loss to determine what the trigger for this problem is.

Any ideas what the problem might be?