customize-face creates too many throwaway faces

[Michael Downes]

In GNU Emacs 20.7.1 (sparc-sun-solaris2.7, X toolkit)
 of Thu Sep 21 2000 on thor
configured using `configure  --with-x'

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:

It seems that when you change the color of a face such as
font-lock-keyword-face by using customize-face, a new face is created
each time you add a letter when typing the new color. This leads to a
lot of extra garbage in the output of list-faces-display:

  bold                          abcdefghijklmnopqrstuvwxyz ...
  bold-italic                   abcdefghijklmnopqrstuvwxyz ...
  custom-button-face            abcdefghijklmnopqrstuvwxyz ...
  custom-changed-face           abcdefghijklmnopqrstuvwxyz ...
   ...                           ...
  default                       abcdefghijklmnopqrstuvwxyz ...
  fg:                           abcdefghijklmnopqrstuvwxyz ...
  fg:B                          abcdefghijklmnopqrstuvwxyz ...
  fg:Bl                         abcdefghijklmnopqrstuvwxyz ...
  fg:Blu                        abcdefghijklmnopqrstuvwxyz ...
  fg:Blue                       abcdefghijklmnopqrstuvwxyz ...
  fg:BlueV                      abcdefghijklmnopqrstuvwxyz ...
  fg:BlueVi                     abcdefghijklmnopqrstuvwxyz ...
  fg:BlueVio                    abcdefghijklmnopqrstuvwxyz ...
  fg:BlueViol                   abcdefghijklmnopqrstuvwxyz ...
  fg:BlueViole                  abcdefghijklmnopqrstuvwxyz ...
  fg:BlueViolet                 abcdefghijklmnopqrstuvwxyz ...

Wouldn't it be better to avoid this by checking first whether the
current string is a valid color name before attempting to create the
face?

Recent input:
- m o d e return escape x c u s t o m i z e - f a c 
e return f o n t - l o c k - k e y w o r d - f a c 
e return down-mouse-1 mouse-1 escape backspace B l 
u e V i o l e t escape x l i s t - f a c e s - d i 
s p l a y return escape x r e p o r t - e m a c s - 
b u g return

Recent messages:
Color "BlueV" undefined
Color "BlueVi" undefined
Color "BlueVio" undefined
Color "BlueViol" undefined
Color "BlueViole" undefined
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