httppeer: use context manager when reading temporary bundle to send Differential Revision: https://phab.mercurial-scm.org/D6784

httppeer: use context manager when writing temporary bundle to send Differential Revision: https://phab.mercurial-scm.org/D6783

rust-cpython: mark unsafe functions as such It wasn't trivial to fix leak_immutable() to be safe since we have to allow immutable operations (e.g. iter()) on the leaked reference. So let's mark it unsafe for now. Callers must take care of the returned object to guarantee the memory safety. I'll revisit this later. I think $leaked<T: 'static> could have a function that converts itself into $leaked<U: 'static> with a given FnOnce(&T) -> &U, where T is $inner_struct, and U is $iterator_type for example.

rust-cpython: pair leaked reference with its manager object Still leak_immutable() is unsafe since leak_handle must live longer than the leaked_ref.

rust-cpython: introduce restricted variant of RefCell This should catch invalid borrow_mut() calls. Still the ref-sharing interface is unsafe.

tests: register test-merge-combination.t as small but slow run-tests.py use file size as an heuristic for test run time. The new `test-merge-combination.t` is a small file that do a lot of processing. As a result it tend to be scheduled really late but delay the full test run by a lot. On an example test run, the one-before-last test completed 279s after the start of the run, while `test-merge-combination.t` finished 355s after it. A 76s delay. This delay can be avoided since `test-merge-combination.t` only got started 175s after the start of the run.

test: allow different result for zstd compression (issue6188) test-repo-compengines fails on big-endian due to different file size, but the repo doesn't seem broken, so allow both sizes. Differential Revision: https://phab.mercurial-scm.org/D6787