simplemerge: make merge_groups() yield only 2-tuples `merge_groups()` currently yields 2-tuples or 4-tuples, making the callers check the first element to decide how to interpret the rest. Let's make it yield only 2-tuples, thereby simplifying life a little for the callers. Differential Revision: https://phab.mercurial-scm.org/D11966

rhg: desambiguate status without decompressing filelog if possible When status is unsure based on `stat()` and the dirstate if a file is clean or modified, we need to compare it against the filelog. This comparison can skip looking at contents if the lengths differ. This changeset optimize this further to deduce what we can about the length if the filelog without decompressing it or resolving deltas. Differential Revision: https://phab.mercurial-scm.org/D11965

filelog: add a comment explaining a fast path in filerevisioncopied() Differential Revision: https://phab.mercurial-scm.org/D11964

rhg: Store p1, p2, and hash in RevlogEntry This avoids a duplicate index lookup Differential Revision: https://phab.mercurial-scm.org/D11963

rhg: RevlogEntry::uncompressed_len is signed The corresponding Python code appears to explicitly check for non-negative values. Differential Revision: https://phab.mercurial-scm.org/D11962

rhg: Expose FilelogEntry that wraps RevlogEntry This can be later extended to access metadata such as `uncompressed_len` without necessarily resolving deltas. Differential Revision: https://phab.mercurial-scm.org/D11961

rhg: Add RevlogEntry::data that does delta resolution This requires keeping a `&Revlog` reference inside the `RevlogEntry` struct. This struct already had the appropriate lifetime parameter. Differential Revision: https://phab.mercurial-scm.org/D11960