"This file was created by an older version of KiCad" in an entirely new project

Description

When I create a new project and open the .kicad_sch file just created, I get a banner saying "This file was created by an older version of KiCad. It will be converted to the new format when saved.". That is obviously untrue.

Steps to reproduce

1. Start KiCad
2. Create a new project, eg. "test_project", with the "Create a new directory for the project" toggle selected.
3. Double click test_project.kicad_sch.
4. Observe the banner.

KiCad Version

Application: Eeschema

Version: (5.99.0-8928-gc255dede17), debug build

Libraries:
	wxWidgets 3.0.5
	libcurl/7.75.0 OpenSSL/1.1.1i zlib/1.2.11 zstd/1.4.8 libidn2/2.3.0 libpsl/0.21.1 (+libidn2/2.3.0) libssh2/1.9.0 nghttp2/1.41.0

Platform: Linux 5.10.5-arch1-1 x86_64, 64 bit, Little endian, wxGTK, KDE, x11

Build Info:
	Date: Feb  7 2021 19:30:45
	wxWidgets: 3.0.5 (wchar_t,wx containers,compatible with 2.8) GTK+ 3.24
	Boost: 1.75.0
	OCC: 7.5.0
	Curl: 7.74.0
	ngspice: 33
	Compiler: GCC 10.2.0 with C++ ABI 1014

Build settings:
	KICAD_SCRIPTING=ON
	KICAD_SCRIPTING_MODULES=ON
	KICAD_SCRIPTING_PYTHON3=ON
	KICAD_SCRIPTING_WXPYTHON=ON
	KICAD_SCRIPTING_WXPYTHON_PHOENIX=ON
	KICAD_SCRIPTING_ACTION_MENU=ON
	KICAD_USE_OCC=ON
	KICAD_SPICE=ON
	KICAD_STDLIB_DEBUG=OFF
	KICAD_STDLIB_LIGHT_DEBUG=OFF
	KICAD_SANITIZE=OFF