Patch merged into coreboot/master: cbfstool: test for duplicate files earlier

the following patch was just integrated into master:
commit 4e54bf93345332fc866b6b8b798a99248edb0698
Author: Patrick Georgi 
Date:   Tue Aug 11 14:35:39 2015 +0200

cbfstool: test for duplicate files earlier

No need to read the file before bailing out.

Change-Id: Ida7226c6ec227e1105724cdb1e5a0927217a69c7
    Signed-off-by: Patrick Georgi 
    Reviewed-on: http://review.coreboot.org/11212
    Tested-by: build bot (Jenkins)
    Reviewed-by: Aaron Durbin

See http://review.coreboot.org/11212 for details.

-gerrit