ISIS-1335: improving error handling in github-pr.sh when the repo to merge from cannot be found
ISIS-1335: improving error handling in github-pr.sh when the repo to merge from cannot be found

sanderginn/isis,estatio/isis,apache/isis,apache/isis,niv0/isis,oscarbou/isis,oscarbou/isis,estatio/isis,estatio/isis,sanderginn/isis,oscarbou/isis,incodehq/isis,estatio/isis,niv0/isis,apache/isis,sanderginn/isis,oscarbou/isis,niv0/isis,niv0/isis,apache/isis,apache/isis,apache/isis,incodehq/isis,incodehq/isis,sanderginn/isis,incodehq/isis