Fix e2e to always specify branch name

As git changes the default from "master" to "main", it's not
predictable.  Now the test owns the decision.

Merge pull request kubernetes#295 from daixiang0/doc

README: add buildx comment

Fix webhook regression: allow -1 to ignore status

Merge pull request kubernetes#282 from thockin/staging

Use new staging GCR

Build updates

Move to go 1.14

Explicitly apt-get update when building

Merge pull request kubernetes#230 from thockin/debian-buster

Bump to debian-base 2.0.0 (buster)

Merge pull request kubernetes#223 from dmarkey/patch-1

Update deployment to use new version which is multi-arch

Merge pull request kubernetes#205 from thockin/git-cat-file

Make revIsHash a bit safer

Merge pull request kubernetes#178 from thockin/master

Fix multi-platform build in Makefile

Merge pull request kubernetes#144 from thockin/fix-ssh

Fix SSH