delta-find: move final debug processing in a `_dbg_process_data` method This will help us making sure we can call the necessary debugging code in alternative codepath.

delta-fine: use the `_debug_search` attribute directly By adjusting the value at creation time, we can avoid the need to use and intermediate variable.

delta-find: move the `gather_debug` logic in a property This will make it simpler to get be reused in multiple places.

tests: check `pulled-delta-reuse-policy=forced` without general delta If general delta is not available, the amount of delta we can reuse at all will be more limited. We check that application still work and does not corrupt the repository.

tree-manifest: allow `debugupgraderepo` to run on tree manifest repo There does not seems to be anything wrong with running the current logic on them. So we remove the limitation.

bundles: clarify streaming v2 bundle usage This seems useful to clarify through the documentation (we were still using debugcreatestreamclonebundle, even though 'hg bundle' is already an option...).

stream-clone: update debugcreatestreamclonebundle helps People to stop using streamv1, so we should point them to alternative in the place where people might find it.

rewrite: simplify the `retained_extras` extra logic First, we move the definition of value outside of the rebase extensions, as this apply to all rebase-like operation and some live in other place (like evolve). Second we make it a simple set, so that it is easy for an extension to add a new value in it. Third, we move the associated logic in core too. That make it easily available to other extensions. Fourth we simplify it usage, as the verbose version of the filtering is just a handful on line long, we are just going to test all the value for updates, so the Projection overlay is not bringing much here. Note that, we make it a module level set, is a key is worth preserving it is probably worth preserving in all cases. This was already the behavior prior to this change.

revlog: fix a bug in revlog splitting Specifically, if the .i.s files are not added to the transaction, then a follow-up modification of such a file records it into transaction as non-empty, which is incorrect.

stream-clone: smoothly detect and handle a case were a revlog is split This detect and handle the most common case for a race condition around stream and revlog splitting. The one were the revlog is split between the initial collection of data and the time were we start considering stream that data. In such case, we repatch an inlined version of that revlog together when this happens. This is necessary as stream-v2 promised a specific number of bytes and a specific number of files to the client. In stream-v3, we will have the opportunity to just send a split revlog instead. Getting a better version of the protocol for stream-v3 is still useful, but it is no longer a blocket to fix that race condition. Note that another, rarer race condition exist, were the revlog is split while we creating the revlog and extracing content from it. This can be dealt with later.

stream-clone: implement decidated `get_streams` method for revlog For revlog, we can do better using the maximum linkrev expected. This approach open the way to dealing with a much larger set of non-trivial changes, like splitting of inline revlogs. We will actually tackle this issue in the next changesets (thanks to this one).

stream-clone: make it the responsability of the store entry to stream content The store entry has more context, this will especially be true when it comes to revlogs. So we move the details of how to retrieve binary content to the StoreEntry. The stream clone code now focus on the protocol bits.

store: declare a `files` method on BaseStoreEntry This will help pytype to type check. We have to move `StoreFile` earlier in the file to use it in the type declaration.

revlog: add a `get_revlog` method This might seen weird, but I actually thing we have been needing this for a long time. There is multiple object that kind of pretend being revlogs while actually wrapping the actual revlog. Since multiple code needs to access the actuel revlog. See documentation for more details. Expect cleanup of various places one the current series is done.

stream-clone: drop the _emit_v2 function It has no user left.

stream-clone: directly use `_entries_walk` to generate stream-v2 This does not requires that much changes and will give us much more flexibility, like improving revlog handling to gracefully handle race situation.

stream-clone: pre-indent some code This make the next changeset clearer.

local-clone: perform the hardlink/copy based from _entries_walk returns We previously used `_v2_walk`. However it is not bringing us much. So lets use the higher level function instead. This will offer us more flexibility with the `_v2_walk` function… like deleting it eventually.

store: cache the file_size when we get it from disk The point of caching `files` is to ensure consistency and avoiding redoing expensive work. So we cache the file_size once retrieved.

store: cache the `files()` return for store entries This make it more efficient to directly use the entries list to retrieve data in various location. It also make the entry record the file size it previously promissed to user code, especially the stream clone code.

stream-clone: introduce a richer TempCopyManager object This replace the previous `copy` callable with a richer object that allow access to the backup path. This will simplify the user code as they won't need to keep and pass around the backup path explicitly.

store: properly compute the targer_id of manifestlog in no-fncache walk Creating RevlogStoreEntry is good, but we need to drop the final `00manifest` part to create something correct.

store: do not drop the final `/` when creating manifestlog instance This bug, inherited from the upgrade code leads to the acces/creation of broken revlog with name `DIRECTORY00manifest.i` instead of `DIRECTORY/00manifest.i` We fix it in its own changeset to preserve the "pure code movement" aspect of the previous changesets.

store: add a `get_revlog_instance` method on revlog entries The upgrade code needs this a lot, and the stream code is about to needs it too. So we start by moving the upgrade code in a more generic location.

stream-clone: add a test that highlight crash on revlog splitting This has been a long running problem, we should have a tests for it.

stream-clone: remove unused code in test-clone-stream.t We are not using the extension we create inline, we are using `tests/testlib/ext-stream-clone-steps.py`. So let us deleted the unused version.

stream-clone: document the ext-stream-clone-steps.py utility extension This extension is useful, let us clarify how to use it.

test-treemanifest: cleanup the test to more easily show server side error This made my life easier debugging.

test: make test-contrib-perf.t more robust Some code path are far too fast now. We raise de number to make sure the run keep to that floor.

safehasattr: pass attribute name as string instead of bytes This is a step toward replacing `util.safehasattr` usage with plain `hasattr`. The builtin function behave poorly in Python2 but this was fixed in Python3. These change are done one by one as they tend to have a small odd to trigger puzzling breackage.