copies: filter invalid copies only at end of pathcopies() (issue6163) copies._filter() filters out copies whose source file does not exist in the start commit or whose target file does not exist in the end commit. We do that after chaining copies with dirstate copies or backward renames from another branch. We also do at the end of the changeset-centric copy tracing. The filtering means that we will remove copies to/from files that did not exist in some intermediate commit. That is inconsistent with what we do if a file has been deleted and then re-added (we allow updating across that). Copying the two first examples from issue6163: @ 4 'rename x to y' | o 3 'add x again' | o 2 'remove x' | | o 1 'modify x' |/ o 0 'add x' @ 4 'rename x to y' | o 3 'add x again' | | o 2 'modify x' | | | o 1 'add x' |/ o 0 'base' When doing `hg rebase -r 1 -d 4` in the first case, it succeeds, but `hg rebase -r 2 -d 4` in the second case does not. That's because we chain and filter via commit 0, which does not have file 'x' in the second case. IMO, that's clearly inconsistent. So this patch removes the filtering step so it only happens at the end. If a file was temporarily removed, whether via a merge base or not, it will now still be considered the same file. That fixes issue6163 for the changeset-centric case. Differential Revision: https://phab.mercurial-scm.org/D6603