I don't know if this is the proper solution, but I was able to google around and find the centos repo where some of those missing rpms are located.
Thanks Al! I will leave this to our rpm experts...
http://vault.centos.org/centos/7.3.1611/cr/x86_64/
If I add this entry to StarlingX.repo
[Starlingx-C7.3.1611-cr] name=Starlingx-CentOS-7.3.1611 - cr baseurl=http://vault.centos.org/centos/7.3.1611/cr/x86_64 gpgcheck=1 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7 enabled=1
and re-copy that to /etc/yum.repos.d/
then the download stage no longer complains about some of the missing entries like python-2.7.5-58 etc..
I will re-run the complete download routine and see if this fixes all the remaining (non src) issues.
Is it possible you submit a patch if it works for you? Adopting the over communication approach, I am logging all the steps and output in this url [0]. Not using etherpad to have a faster edit / easy formatting. [0] https://github.com/xe1gyq/starlingx/blob/master/DeveloperGuide.md