fix check_target_files_signatures
fix check_target_files_signatures

common.UnzipTemp now returns a 2-tuple instead of just a string.

Bug: 3398407
Change-Id: Ifd0408283aaa15752caa549f4510a0a3db03c3fd

pranav01/platform_manifest,fallouttester/platform_manifest,xorware/android_build,xorware/android_build,xorware/android_build,hagar006/platform_manifest,ND-3500/platform_manifest,xorware/android_build,see4ri/lolili,RR-msm7x30/platform_manifest,Hybrid-Power/startsync,xorware/android_build,knone1/platform_manifest