tags 38812 patch
thanks

> This bug affects the customizations that happen before customizing
> custom-enabled-themes, that's why in the init file is necessary to have
one
> customization before and one after, to be able to compare the results.
> Since custom maintains the arguments to custom-set-variables in alphabetic
> order, all variables that would be sorted before custom-enabled-themes
> are affected by this bug.

When custom-enabled-themes is customized, its set function enable the
themes.  When that happens, custom recalculates the value of the
variables, according to the enabled themes, with
custom-theme-recalc-variable.  For variables that already have a
theme-value property (i.e., the variables that were customized with
custom-set-variables before customizing custom-enabled-themes),
custom-theme-recalc-variable ends up putting in the 'saved-value
property the same cons cell that is in the 'theme-value property.

Customizing in a session changes the 'theme-value property of the
customized variable, and the above has the effect of changing the
'saved-value property as well.

A possible fix is to make custom-variable-theme-value return a new list.
I attach a patch that does that.

Best regards,
Mauro.