local: set DISABLE_UEFI_32=1

That's only useful when using an official d-i build (i.e. when
DI_WWW_HOME is unset), but let's have that setting in place since the
local, partial mirror doesn't include i386: that makes it easier to
switch back and forth between a local and an official d-i build.

CONF.sh

@@ -228,6 +228,7 @@ export JIGDO_CHECKSUM="md5"
 # firmware like Baytrail or some models of Apple iMac. To disable
 # this, uncomment the following:
 # export DISABLE_UEFI_32=1
+export DISABLE_UEFI_32=1
 
 # Keyring (defaults):
 #export ARCHIVE_KEYRING_PACKAGE=debian-archive-keyring