revset: add a predicate for finding converted changesets This selects changesets added because of repo conversions. For example hg log -r "converted()" # all csets created by a convertion hg log -r "converted(rev)" # the cset converted from rev in the src repo The converted(rev) form is analogous to remote(id), where the remote repo is the source of the conversion. This can be useful for cross referencing an old repository into the current one. The source revision may be the short changeset hash or the full hash from the source repository. The local identifier isn't useful. An interesting ramification of this is if a short revision is specified, it may cause more than one changeset to be selected. (e.g. converted(6) matches changesets with a convert_revision field of 6e..e and 67..0) The convert.hg.saverev option must have been specified when converting the hg source repository for this to work. The other sources automatically embed the converted marker.