tests: remove hg10 requirement from test-check-pylint.t Since pylint does its own directory traversal to find files to check and doesn't use hg locate command, this requirement is not valid. See also a29f071751df.

tests: add hg10 requirement to test-check-module-imports.t This requirement exists to make sure for hg has locate command, which is used in this test file for getting a list of files to check. Since in theory current versions of tests could be run on older hg, it doesn't hurt to mark even this version requirement (as old as it is). See also: a29f071751df.

tests: work around non-thread-safeness of sysconfig.get_config_var()

worker: implement _blockingreader.readinto() (issue6444) The core logic for readinto() was already implemented in read(), so this is mostly extracting that code into its own method. Another fix for issue6444 was committed to the stable branch: 2fe4efaa59af. That is a minimal fix that implements readinto() only on Python versions that require readinto() (3.8.0 and 3.8.1), which is the right approach for the stable branch. However, I think that this changeset has its value. It improves performance in cases when pickle can use readinto(), it reduces code duplication compared to the other patch, and by defining readinto() on all Python versions, it makes behavior more consistent across all Python versions. This changesets reverts the other change.

worker: stop relying on garbage collection to release memoryview On CPython, before resizing the bytearray, all memoryviews referencing it must be released. Before this change, we ensured that all references to them were deleted. On CPython, this was enough to set the reference count to zero, which results in garbage collecting and releasing them. On PyPy, releasing the memoryviews is not necessary because they are implemented differently. If it would be necessary however, ensuring that all references are deleted would not be suffient because PyPy doesn’t use reference counting. By using with statements that take care of releasing the memoryviews, we ensure that the bytearray is resizable without relying on implementation details. So while this doesn’t fix any observable bug, it increases compatiblity with other and future Python implementations.

worker: add docstring to _blockingreader

worker: explain why pickle reading stream has to be unbuffered

bundle: quick fix to ludicrous performance penalty We tried a `hg bundle --base ':(tip^)' --rev 'all()'` on a large repository and it spent 3 minutes on this 2 list comprehensions. This change remove this cost. There are still a lot of low hanging fruits as the command still take 30 seconds. However this is a trivial patch with a massive speedup so I'll just sent it.

deltas: add a debug-delta-find command to analyse delta search See command documentation for details. For some reason, pytype is confused by our usage of None/deltainfo variable, so I had to quiet it.

deltas: add a `debug.revlog.debug-delta` config option enable output This provide a way to enable the code introduced in the previous changeset. This will provide a large amount of output when applying a bundle with details about each delta "computation".