PCB Editor: Curved zones are poorly filled in after launch

Description

Curved polys are poorly filled in after launch. They need to be refilled to be displayed correctly. After saving and reopening, they are incorrectly filled again.

Steps to reproduce

vokoscreen-2021-08-06_16-16-35

KiCad Version

Application: KiCad PCB Editor

Version: 5.99.0-unknown-3747cb50c9~131~ubuntu20.04.1, release build

Libraries:
	wxWidgets 3.0.4

Platform: Linux 5.4.0-80-generic x86_64, 64 bit, Little endian, wxGTK, cinnamon, x11

	wxWidgets: 3.0.4 (wchar_t,wx containers,compatible with 2.8) GTK+ 3.24
	Boost: 1.71.0
	OCC: 7.3.0
	Curl: 7.68.0
	ngspice: 31
	Compiler: GCC 9.3.0 with C++ ABI 1013

Build settings:
	KICAD_USE_OCC=ON
	KICAD_SPICE=ON