revset: add origin() predicate This predicate is used to find the original source of csets created by a graft, transplant or rebase --keep. If a copied cset is itself copied, only the source of the original copy is selected. hg log -r origin() # all src csets, anywhere hg log -r origin(branch(default)) # all srcs of copies on default By following through different types of copy commands and only selecting the original cset, the implementation differences between the copy commands are hidden. (A graft of a graft preserves the original source in its 'extra' map, while transplant and rebase use the immediate source specified for the command). Given a repo with a cset S that is grafted to create G(S), which itself is grafted to become G(G(S)) o-S / o-o-G(S) \ o-G(G(S)) hg log -r origin( G(S) ) # { S } hg log -r origin( G(G(S)) ) # { S }, NOT { G(S) } Even if the last graft were a transplant hg log -r origin( T(G(S)) ) # { S } A rebase without --keep essentially strips the source, so providing the cset that results to this predicate will yield an empty set. Note that the convert extension does not currently update the 'extra' map in its destination csets, and therefore copies made prior to the convert will be unable to find their source.