bug#12667: 24.2; defcustom changed in lexical-binding

[Stefan Monnier <monnier@iro.umontreal.ca>]

> 1. Load the attached bigbug.el
> 2. open it in emacs and edit the definition of
>    clang-project-default-settings, for example, remove "-v"
> 3. C-M-x the defcustom
> 4. C-h v clang-project-default-settings to show:

> ,----
> | clang-project-default-settings is a variable defined in `bigbug.el'.
> | Its value is (("SDKROOT" . "iphoneos")
> |  ("OTHER_CFLAGS" "-ferror-limit=0" "-ObjC" "-DDEBUG=1" "-v"))
> | 
> | Original value was 
> | (("SDKROOT" . "iphoneos")
> |  ("OTHER_CFLAGS" "-ferror-limit=0" "-ObjC" "-DDEBUG=1"))
> | 
> | 
> | Documentation:
> | FIXME
> | 
> | You can customize this variable.
> `----

I can't reproduce it here.
I did "src/emacs -Q -l ~/tmp/bigbug.el ~/tmp/bigbug.el"
then removed the "-v" and did C-M-x and then C-h v and it showed the
value did not have "-v" any more (and the original value was not
displayed because it's equal to the current value).

Can you try and figure out what's the difference between me test case
and your test case, to see what triggers the problem?


        Stefan