bookmark: don't allow integers as bookmark/branch/tag names Bookmarks/branches/tags shouldn't be allowed to be integers because that overlaps with revision numbers. Right now if a user created one they can't use it anyway because the revision numbers take precedence. The check only happens when creating a new bookmark/etc from a command so it shouldn't affect existing bookmarks/branches/tags or importing branches from git. This fix was prompted by us having a user create a bookmark named "404" then accidentally checkout a very old version of our repository.