Merge branch 'jk/clone-unborn-confusion' into maint

"git clone" from a repository with some ref whose HEAD is unborn did not set the HEAD in the resulting repository correctly, which has been corrected. source: <YsdyLS4UFzj0j/wB@coredump.intra.peff.net> * jk/clone-unborn-confusion: clone: move unborn head creation to update_head() clone: use remote branch if it matches default HEAD clone: propagate empty remote HEAD even with other branches clone: drop extra newline from warning message