Problems on Windows with INC being overridden

Hi,

I've only just read "MakeMaker is DOOMED" so perhaps I'm flogging a dead 
horse but then again, it was dated 2003.

Can anyone tell me if putting INC on the command line as in

perl Makefile.PL INC=c:\fred

is supposed to override INC in the Makefile.PL?

I examine $opts{INC} in my Makefile.PL and add a path to it via the 
CONFIGURE method but this seems to be ignored when INC is specified on 
the command line and ok when it isn't.

When people are using cpan -i on Windows in Strawberry Perl cpan seems 
to be adding INC=path to the command line.

e.g. Makefile generated without INC on the command line ends up containing:

#   MakeMaker ARGV: ()
#     INC => q[]
#     INC => q[ -IC:\strawberry\perl\site\lib\auto\DBI]
INC =  -IC:\strawberry\perl\site\lib\auto\DBI

but when INC is specified:

#   MakeMaker ARGV: (q[LIBS=-LC:\strawberry\c\lib], 
q[INC=-IC:\strawberry\c\include])
#     INC => q[]
#     INC => q[ -IC:\strawberry\perl\site\lib\auto\DBI]
INC = -IC:\strawberry\c\include

Thanks.

Martin