So please don't close this EPIC until we have acceptance criteria of auto-merging poll upstream sources.
I understand there can be sometimes failures, but it should work in general.
Maybe you should include in this epic the card opened on tracking simplification of the reposync files.

on 4.2 fails on
Invoking jobs / check-patch.basic_suite_4.2.el7.x86_64 / 004_basic_sanity.check_snapshot_with_memory
on master fails on
check-patch.he-basic-ansible_suite_master.el7.x86_64 / 008_restart_he_vm.restart_he_vm

so it can't be merged automatically anyway

the changes in the files are minor (extra space at the end, or location of exclude line

I think once we will see a pass tests for this updates, we can move to auto merge

I assumed this will be fixed once we enabled the 'auto merge' option and poll upstream sources will be merged without issues on a daily basis, is that the case now? or we're still tweaking the nightly patches to pass?

Fixed code review
Added a change to support repofiles templates.
Instead of stripping the original repo files we will use a template repofiles.
Any changes will be in these template files. File name structure <repofilename>.in
build_reposync_config.sh also support getting list of files (or *), but not a directory.
No need for the reposync file to provide the -c
Additional packages are provided with -p <pkg1> -p <pkg2> ....

Added to build_reposync_config.sh to support getting multiple files / directory