Semantically unchanged CST nodes do not always roundtrip safely

[sirosen]

Probably a slight misuse of libcst APIs:

-case y, z:
+case [y, z]:

[sirosen]

Found another fun case in some encoding tests:

 # -*- encoding: koi8-r  -*-
-test = "ðÏÚÎÁÎÉÅ ÂÅÓËÏÎÅÞÎÏÓÔÉ ÔÒÅÂÕÅÔ ÂÅÓËÏÎÅÞÎÏÇÏ ×ÒÅÍÅÎÉ.
+test = "Познание бесконечности требует бесконечного времени.

(Source: CPython, Lib/test/encoded_modules/module_koi8_r.py)

[sirosen]

Tracked part of this down to what appears to be a libcst bug:
Instagram/LibCST#1096

[sirosen]

The encoding issue was fixed: 66d66cb

All that's left is to pick up a new libcst release to fix match handling.