relnotes: add 6.6.3

tests: fix nondeterministic test failure in test-contrib-perf.t It turns out (not too shockingly!) the kernel sometimes has some work to do, perhaps at the very least context-switching, so asserting the system time is 0.000000 doesn't work.

grep: restore usage of --include/--exclude options The refactor in 4a73df6eb67d accidentally forgot to transform the opts argument for walkopts into a byteskwargs. This resulted in its options being ignored. In particular, the -X/-I pair of options was missing. A simple fix restores its usage. Tests included, of course.

rust-changelog: don't panic on empty file lists

tests: use sha256line.py instead of /dev/random in test-censor.t (issue6858) Sometimes the systems that run our test suite don't have enough entropy and they cannot produce target file of the expected size using /dev/random, which results in test failures. Switching to /dev/urandom would give us way more available data at the cost of it being less "random", but we don't really need to use entropy for this task at all, since we only care if the file size after compression is big enough to not be stored inline in the revlog. So let's use something that we already have used to generate this kind of data in other tests.

tests: make sha256line.py available for all tests This was previously only used in test-revlog-delta-find.t, but it will be useful (and used) in other tests that might need to generate poorly-compressible files.

delta-find: pass the full deltainfo to the _DeltaSearch class Having more information is better, so we pass it directly.

delta-find: move sparse-revlog pre-filtering in the associated class Lets move the specialized code in the specialized class.

delta-find: move sparse-revlog delta checks in the associated class Lets move the specialized code in the specialized class.

delta-find: split the _DeltaSearch class in two We now have things sliced small enough to have two class that use different `_iter_groups` implementation to encode their different logic. The filtering code remains to be moved, but I would rather keep this changeset simple and move them in the next.

delta-find: finish reworking the snapshot logic and drop more layer The refining logic only applies to the snapshot logic, and this is now all contained in a dedicated method. Along the way, we drop the refined_groups // raw_groups layer as they no longer make sense. The result is a more explicit `iter_groups` method. This conclude the splitting and simplification of the groups generation. We are now ready to dispatch this in more diverse classes.

delta-find: move the base of the delta search in its own function That logic is complicated enough that is is worth puting in its own function. Another method will be introduced in the next changeset to deal with the actual refining.

delta-find: move the emotion of prev in a dedicated method After splitting the filtering, and with the `_candidate_groups` layer removed, we can start splitting the group generation too. This helps to organize this code and make it easier to modifying the future.

delta-find: move the emotion of parents in a dedicated method After splitting the filtering, and with the `_candidate_groups` layer removed, we can start splitting the group generation too. This helps to organize this code and make it easier to modifying the future.

delta-find: explicitly deal with usage of the cached revision We can remove this from the general logic path and directly deal with this corner case early. This result in a small change in test-generaldelta.t as it turns out that: - at commit time we (sometimes) precompute a delta against p1 and pass it as the cached delta. - since cached delta where going through the same filtering as everything, we could "optimize" the base if it applied to an empty delta, resulting in not using the pre-computed delta. The simpler logic fix the second item, making the cached delta base always actually tested when requested. Note that the computation of a fast delta against p1 only is questionable, but looking into that is out of scope for this series.