New comment by st3r4g on void-packages repository

https://github.com/void-linux/void-packages/issues/15751#issuecomment-546078876

Comment:
It tries to install both versions of the `matplotlib-data` subpackage, which contains many files that are the same. Apparently `replaces="python-matplotlib-data<3.0.0"` is not enough when installing as part of the same transaction. Maybe this didn't throw errors before because iirc a check for conflicting files in the same transaction has been added only recently.