However, default system installations of Vim that are compiled with Python versions that are considered to be the stable default for the OS, which usually meant Python 2.6 or 2.7 until recently.

$ vim --version VIM - Vi IMproved 8.1 (2018 May 18, compiled Nov 21 2018 21:36:44) Included patches: 1-535 ... the symbol in question is defined in the non-stripped version ... grep PyByteArray_Type ...