Router laying tracks slightly tighter than DRC allows (was: lots of very near DRC collisions (rounding errors?))

Description

The attached project has a large number of very close collisions in DRC:

All are 1µm off or less. They were all placed with the router in "walk around" or "highlight collisions" without "allow DRC violations". The router and DRC appear to disagree on them — DRC fails them, but the router passes them.

pd2530-regulator.zip

Steps to reproduce

Run DRC on the attached project
Go to one of the clearance violations and try to adjust the track. The router will not highlight a collision on it, as it believes the route is already valid.

KiCad Version

Application: KiCad PCB Editor arm64 on arm64

Version: 7.99.0-1326-ge4fe27993e, release build

Libraries:
	wxWidgets 3.2.2
	FreeType 2.12.1
	HarfBuzz 5.3.1
	FontConfig 2.14.0
	libcurl/7.88.1 (SecureTransport) LibreSSL/3.3.6 zlib/1.2.11 nghttp2/1.51.0

Platform: macOS Ventura Version 13.4 (Build 22F66), 64 bit, Little endian, wxMac

Build Info:
	Date: Jun  4 2023 01:20:58
	wxWidgets: 3.2.2 (wchar_t,wx containers)
	Boost: 1.80.0
	OCC: 7.6.3
	Curl: 7.77.0
	ngspice: 40
	Compiler: Clang 13.0.0 with C++ ABI 1002

Build settings:

Edited Jun 06, 2023 by Alexis V L