bookmarks: add explicit option to list bookmarks of the given names
This is a generalized form of the --active option.
A redundant sorted() call is removed. There was no point to update dict items
in lexicographical order.
Set up
$ hg init repo
$ cd repo
Try to import an empty patch
$ hg import --no-commit - <<EOF
> EOF
applying patch from stdin
abort: stdin: no diffs found
[255]
No dirstate backups are left behind
$ ls .hg/dirstate* | sort
.hg/dirstate