gh-145743: Fix inconsistency after calling Struct.init() with invalid format (GH-145744)

Only set the format attribute after successful (re-)initialization.

Serhiy Storchaka committed 1mo ago

3f33bf83e8496737b86333bc9ec55dc3ccb3faca

Parent: bf4017b

Committed by GitHub <noreply@github.com> on 3/10/2026, 4:29:23 PM

gh-145743: Fix inconsistency after calling Struct.__init__() with invalid format (GH-145744)