Symbol Editor: Reverting modifications on symbol with derived symbols, derived symbols are displayed wrong

Description

When modifying and reverting modifications on a symbol in Symbol Editor, if that symbol has "derived symbols" (previously known as "Aliases"), the derived symbols are displayed wrong in both the left libraries browser and the window's main edition zone.

• The left libraries browser doesn't show italic names for currently modified/reverted symbol's derived symbols.
• And in the main edition zone, when loading any one of the derived symbols of the reverted symbol, no graphic element is displayed. Only text fields are displayed.

See attached video: 2022-02-08_10-12-08.mkv

Steps to reproduce

1. Open Symbol Editor
2. In left libraries browser, select and open by double-clicking on its name a symbol that has derived symbols
3. Modify that symbol (you can Ctrl-Z the modification)
4. In "File" menu, click on "Revert" entry
5. Check that, in the left libraries browser, the derived symbol names of the reverted symbol are not in italic anymore
6. In left libraries browser, select and open by double-clicking on its name one of the derived symbol which is name isn't italic anymore
7. Check that, in main edition zone, there's no graphic element displayed, only text fields are displayed

KiCad Version

Application: KiCad Symbol Editor

Version: 6.0.1-79c1e3a40b~116~ubuntu20.04.1, release build

Libraries:
	wxWidgets 3.0.4

Platform: Linux 5.4.0-96-generic x86_64, 64 bit, Little endian, wxGTK, xubuntu, x11

	wxWidgets: 3.0.4 (wchar_t,wx containers,compatible with 2.8) GTK+ 3.24
	Boost: 1.71.0
	OCC: 7.5.2
	Curl: 7.81.0
	ngspice: 31
	Compiler: GCC 9.3.0 with C++ ABI 1013

Build settings:
	KICAD_USE_OCC=ON
	KICAD_SPICE=ON