create_local_branch: make check for remotes/origin/$BRANCH more explicit
create_local_branch: make check for remotes/origin/$BRANCH more explicit

We we can't do just a grep for "remotes/origin/debian when"
trying to check out the "debian" branch, instead we need to
check for a trailing '$' at the end of the grep string to
avoid matching e.g. remotes/origin/debian-lenny then.

Thanks: Axel Beckert

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