Code review comment for lp:~vila/bzr/323111-orphan-non-versioned-files

this bzr-orphans dir must be ignored by bzr by default,
i.e. it should not be accidental be added with an unqualified `bzr add` .

we used to have this problem with upgrading, so now the first backup
dir we make is
backup.bzr.~1~ which is ignored by default, and you can have more than one.

so either call it bzr-orphans~ or bzr-orphans~1~ or add bzr-orphans to
the default ignore list. (I think its fine if thats done a followup)