Merge branch 'jc/name' into next

* jc/name:
  core.warnambiguousrefs: warns when "name" is used and both "name" branch and tag exists.
  contrib/git-svn: allow rebuild to work on non-linear remote heads
  http-push: don't assume char is signed
  http-push: add support for deleting remote branches
  Be verbose when !initial commit
  Fix multi-paragraph list items in OPTIONS section
  http-fetch: nicer warning for a server with unreliable 404 status