colcon build --symlink-install requres for every change in .py files

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Hello,

This is maybe very stupid question but to me it is very strange.

I apt installed ros-foxy on my SBC with ubuntu 20.04. Launching, running nodes works just fine as expected however whenever I make changes in any .py files, it requires colcon build --symlink-install again.

This 'colcon build --symlink-install' normally worked before as it doesn't require build process for any changes in python package. But all of a sudden it simply not working. Is there a way to make changes in launch.py or any .py file just reflect in runtime?

Thanks,