Environment variables hard to redefine

I’m trying to redefine the new environment variables introduced for KiCad 6 (e.g. KICAD6_3DMODEL_DIR, KICAD6_FOOTPRINT_DIR, KICAD6_SYMBOL_DIR) so that they point to my personal forks of the libraries.

Using Preferences > Configure Paths issues a warning:

This path was defined externally to the running process and will only be temporarily overwritten.

Thanks to the help by @sethhillbrand on the forum, I found they are defined on kicad-nightly-env.sh.

That file is owned by root and it will probably get overwritten with every update of KiCad, so it gets hard to redefine those variables.

Is it necessary to define those variables externally? If not, could we not define them?

Thanks!

Application: KiCad

Version: 5.99.0-unknown-430310bb75~115~ubuntu20.04.1, release build

Libraries:
	wxWidgets 3.0.4
	libcurl/7.68.0 OpenSSL/1.1.1f zlib/1.2.11 brotli/1.0.7 libidn2/2.2.0 libpsl/0.21.0 (+libidn2/2.2.0) libssh/0.9.3/openssl/zlib nghttp2/1.40.0 librtmp/2.3

Platform: Linux 5.8.0-43-generic x86_64, 64 bit, Little endian, wxGTK, gnome-xorg, x11

Build Info:
	Date: Feb 10 2021 08:06:39
	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_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