I don't want to break the rule. I just request that 3 identified ppl
from BibLibre can sign-off in the name of the customer (I like the Proxy
term).

In case this wasn't clear, I have absolutely no objection to this, provided the customer sticks a note on the bug so the history is clear. Actually, if I have time, I'd like to extend your sandbox code to allow libraries to sign off directly from the sandbox. I'd also like to add features to allow the sandbox system to handle testing indexing. Better to have your project managers test other patches than spend time inserting "Signed-off-by" lines for libraries that are using the sandbox but don't understand git. :)