context: reuse changectx._copies() in all but workingctx This moves the dirstate-specific _copies() implementation from committablectx into workingctx where it should be (I think all dirstate-specific stuff should be moved into workingctx). The part of changectx._copies() that is for producing changeset-wide copy dicts from the filectxs is moved into basectx so it's reused by the other subclasses. The part of changectx._copies() that's about reading copy information from the changeset remains there. This fixes in-memory rebase (and makes `hg convert` able to write copies to changesets). Differential Revision: https://phab.mercurial-scm.org/D6219

overlayworkingctx: don't include added-then-deleted files in memctx If a file (such as a .orig file) is temporarily added to the overlayworkingctx and then deleted, it's still going to be in the _cache dict. In tomemctx(), we created the list of files from _cache.keys(), so the memctx.files() would include the temporary file. That was fine because the list of files was only used in localrepo.commitctx() (I think), where there's an extra filtering of incorrectly removed files (annotated with an inaccurate "update manifest" comment). I'd like to call memctx.files() in another case, but first we need to make it accurate. Differential Revision: https://phab.mercurial-scm.org/D6361