bookmarks: allow pushing active bookmark on new remote head (
issue5236)
Before 'hg push -B .' on new remote head complained with:
abort: push creates new remote head ...
It was because _nowarnheads was not expanding active bookmark
name, so it didn't add active bookmark "proper" name to no
warn heads list.
ERROR: FIXME: This is a known failure of filelog.size for data starting with \1\n
OK.