generate-git-snapshot: make sure all files are up2date through running "git pull"
generate-git-snapshot: make sure all files are up2date through running "git pull"

For some reason the Git plugin in Jenkins doesn't run the
'git pull' for us, so while the files are fetched already
they aren't present in the working directory yet.
So let's make sure we actually have the files we're claiming
to work with.

hetznerZA/jenkins-debian-glue,tanglu-org/jenkins-tanglu-buildkit,bmiklautz/jenkins-debian-glue,zeha/jenkins-debian-glue,n054/jenkins-debian-glue,n054/jenkins-debian-glue,wikimedia/operations-debs-jenkins-debian-glue,jbfavre/jenkins-debian-glue,tanglu-org/jenkins-tanglu-buildkit,kartikm/jenkins-debian-glue,webtrekk-kane/jenkins-debian-glue,hashar/jenkins-debian-glue,bmiklautz/jenkins-debian-glue,wikimedia/operations-debs-jenkins-debian-glue,tanglu-org/jenkins-tanglu-buildkit,linuxmaniac/jenkins-debian-glue,webtrekk-kane/jenkins-debian-glue,vorlock/jenkins-debian-glue,jbfavre/jenkins-debian-glue,tonin/jenkins-debian-glue,hetznerZA/jenkins-debian-glue,mika/jenkins-debian-glue,tonin/jenkins-debian-glue,cclausen/jenkins-debian-glue,linuxmaniac/jenkins-debian-glue,zeha/jenkins-debian-glue,hashar/jenkins-debian-glue,vorlock/jenkins-debian-glue,cclausen/jenkins-debian-glue,kartikm/jenkins-debian-glue,mika/jenkins-debian-glue