Investigate cloud build trigger

[priyawadhwa]

In bug #217 and this bug the executor image tagged at latest was different from the image tagged with the most recent commit, and with the image built locally at HEAD, even though they should all be the same.

container-diff output of the locally built executor and the actual image at latest looks like this:

$ container-diff diff daemon://gcr.io/kaniko-project/executor:latest gcr.io/kaniko-project/executor --type file

-----File-----

These entries have been added to gcr.io/kaniko-project/executor:latest:
FILE                                                     SIZE
/.config                                                 25B
/.config/gcloud                                          25B
/.config/gcloud/docker_credential_gcr_config.json        25B
/root                                                    186B
/root/.docker                                            186B
/root/.docker/config.json                                186B
/usr                                                     11.3M
/usr/local                                               11.3M
/usr/local/bin                                           11.3M
/usr/local/bin/docker-credential-ecr-login               6.3M
/usr/local/bin/docker-credential-gcr                     4.9M

These entries have been deleted from gcr.io/kaniko-project/executor:latest:
FILE                                                            SIZE
/kaniko/.config                                                 25B
/kaniko/.config/gcloud                                          25B
/kaniko/.config/gcloud/docker_credential_gcr_config.json        25B
/kaniko/.docker                                                 186B
/kaniko/.docker/config.json                                     186B
/kaniko/docker-credential-gcr                                   4.9M
/workspace                                                      0

These entries have been changed between gcr.io/kaniko-project/executor:latest and gcr.io/kaniko-project/executor:
FILE                    SIZE1        SIZE2
/kaniko/executor        37M          23.6M

In both cases I reran the build trigger to fix the problem, but we should investigate why this keeps happening.