Preservation of "vendor" and "unlabeled" branches as source of other preserved branches

[brevilo]

Right now the vendor and unlabeled (no typo here) branches are excluded. However there are a number of preserved branches and tags (up to 5.9 I think) that got populated based on these branches. Don't we have to keep them then?

Examples:

• vendor: r11659 or r12315
• unlabeled: r10640

Note: if we decide to keep the unlabeled branches we have to put them into a (at least) 2-level hierarchy because there're a lot of them, e.g.: unlabeled/1.285.2