Only report incomplete sync on the affected repos

[ggatward]

Currently sat_export complains on EVERY repo if only one RPM repo has an incomplete sync. Script should only alert once about incompletes and skip the one that is affected, allowing all others to complete export.

[adam-kosseck]

We sync a large number of repositories every night, but only export a subset of these repositories (using exports.yml to define this subset).

The export script currently fails if any repository fails to sync - even if those repositories are not being exported.

The export script should only check the sync status of the repositories it is exporting.