[3.10] bpo-44838: Refine the custom syntax errors for invalid 'if' expressions (GH-27615). (GH-27616)



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(cherry picked from commit f5cbea6b1b5fc39cca377c6cc93f222916015fc4)

Co-authored-by: Pablo Galindo Salgado <Pablogsal@gmail.com>

Automerge-Triggered-By: GH:lysnikolaou
4 files changed