revlog: pass a transaction object to `rewrite_sidedata` The `_writing` context need one, so we update the function signature before considering using `_writing` in rewrite_sidedata. Differential Revision: https://phab.mercurial-scm.org/D10607

revlog: rename variable in `rewrite_sidedata` to match other code Let's call the index file object and `ifh` and the data file object `dfh` as the rest of the revlog code. This will make future change clearer. Differential Revision: https://phab.mercurial-scm.org/D10606

revlog: introduce a mandatory `_writing` context to update revlog content Before this change, various revlog methods where managing the opening and closing of the revlog files manually and passing the file descriptor alors the call path. To simplify the tracking of the write operation by a future docket, we need something more organised. As a result, we introduce a `revlog._writing` context manager that will wrap each revlog update operation. The file descriptor are kept in the existing `revlog._writinghandles` parameter that was already used by the `addgroup` logic. All this change is internal to the revlog only, the "public" interface is not affected. The `addrevision` and `addgroup` logic are still responsible for setup up this context. However this new context give us multiple benefits: * all writer use a same, unified, logic, * this context is programmatically enforced, * each write "session" as a clearly identified start and end. The post-pull sidedata update logic is still doing writing by end and will be adjusted in a later changesets. This change affect the concurrency checker test, because register the state of the file in the transaction sooner in `addrevision` (about as early as what `addgroup` would do), so the abort is rollbacking the other commit. I don't want to weaken the current main logic. Differential Revision: https://phab.mercurial-scm.org/D10605

revlog: preindent some code in _enforceinlinesize Indenting this beforehand will make a future changeset much simpler. Differential Revision: https://phab.mercurial-scm.org/D10604

revlog: preindent some code in addgroup Indenting this beforehand will make a future changeset much simpler. Differential Revision: https://phab.mercurial-scm.org/D10603

pyoxidizer: use Python 3.9 (BC) Newer versions of PyOxidizer use Python 3.9 by default. We previously pinned the version to 3.8 to facilitate porting to a new PyOxidizer version and diffing results. Now that the porting work is complete, let's bump Python to Python 3.9. This will effectively change our Windows Inno and WiX Python 3 installers from Python 3.8 to 3.9. .. bc:: Windows .msi and .exe installers now use Python 3.9 instead of Python 3.8. Differential Revision: https://phab.mercurial-scm.org/D10689