Fix missing validation for Branches::CreateService
What does this MR do and why?
Contributes to #454533 (closed)
Problem
Branches::CreateService
doesn't validate the presence of ref
parameter. As a result, Gitaly responds with unhandled
GRPC::InvalidArgument: 3:empty start point
error.
Solution
Add an error handler to verify ref
presence.
Edited by Vasilii Iakliushin