A820 cm11 编译出错 求解

using device-specific extensions in device/lenovo/common
unable to load device-specific module; assuming none
using prebuilt recovery.img...
using prebuilt boot.img...
running: imgdiff -b /tmp/targetfiles-pLlRSW/SYSTEM/etc/recovery-resource.dat /tmp/tmpLI2RH0 /tmp/tmprvguZi /tmp/tmp7IWX_O
WARNING: failure running ['imgdiff', '-b', '/tmp/targetfiles-pLlRSW/SYSTEM/etc/recovery-resource.dat']:
Traceback (most recent call last):
File "./build/tools/releasetools/ota_from_target_files", line 1132, in <module>
main(sys.argv[1:])
File "./build/tools/releasetools/ota_from_target_files", line 1100, in main
WriteFullOTAPackage(input_zip, output_zip)
File "./build/tools/releasetools/ota_from_target_files", line 543, in WriteFullOTAPackage
MakeRecoveryPatch(OPTIONS.input_tmp, output_zip, recovery_img, boot_img)
File "./build/tools/releasetools/ota_from_target_files", line 405, in MakeRecoveryPatch
_, _, patch = d.ComputePatch()
TypeError: 'NoneType' object is not iterable
make: *** [/media/ab2cc75d-2fe6-4416-beef-bdde05fbd089/feifei/vbox_share/CM_files/A820_CM11/out/target/product/a820/cm_a820-ota-1af915a721.zip] Error 1