One-time import acts on all series for the branch

AFAICS, requesting a one-time translations import from a branch to a productseries forces a translations import from that branch to all productseries attached to that branch, regardless of their import setting.

This probably won't affect many people, but it would in a situation where two separate release series are based on the same branch, and manage their translations separately. The one-time import on one series would also do the same import on the other series.

This could be prevented by replacing the force_translations_import flag in the branch job's metadata with the name or id of the productseries that the one-off import is for. Then the one-time import acts on the productseries instead of on the branch as the UI suggests.