util: fix ellipsis() not to break multi-byte sequence (issue2564)
It tries to convert localstr to unicode before truncating.
Because we cannot assume that the given text is encoded in local encoding,
it falls back to raw string in case of unicode error.
$ rm -rf a
$ hg init a
$ cd a
$ echo a > a
$ hg ci -Am0
adding a
$ hg tag t1 # 1
$ hg tag --remove t1 # 2
$ hg co 1
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg tag -f -r0 t1
$ hg tags
tip 3:a49829c4fc11
t1 0:f7b1eb17ad24