Allow to clone only certain branches/tags when forking a project
Description
When forking a project, all its branches and tags are copied to the new project, but in most cases I am interested in one branch only.
E.g. on projects like the linux kernel, >1500 globally visible tags will be cloned into the new project. This make it difficulty to work with it and in most cases, I delete the branches/tags immediately after cloning. Unfortunately, every single 'delete' operation will be counted as an 'activity' and pollutes the "activity" list.
These objects will not be removed at all but kept in the 'keep-ref' namespace so that disk space is not reclaimed.
Proposal
Allow to copy only a single branch/tag when forking a project.