On Tue, 10 Apr 2018 19:29:18 +0300 Serhiy Storchaka email@example.com wrote:
A bugfix release can fix bugs in bytecode generation. See for example issue27286.  The part of issue33041 backported to 3.7 and 3.6 is an other example.  There were other examples of compatible changing the bytecode. Without bumping the magic number these fixes can just not have any effect if existing pyc files were generated by older compilers. But bumping the magic number in a bugfix release can lead to rebuilding every pyc file (even unaffected by the fix) in distributives.
Sure, but I don't think rebuilding every pyc file is a significant problem. It's certainly less error-prone than cherry-picking which files need rebuilding.