fix the 7-bytes binary decoding error

Suppe there is 7-bytes array,and the highest bit of last byte is '1'. for example, "0x11, 0x11, 0x11, 0x11, 011, 0x11, 0x80". Then we invoke EncodeBinary and DecodeBinary on this array.
EncodeBinary works, but in DecodeBinary, before breaking for loop, variabl 't' is not updated to 0, it wil cause panic in line185.

the fix is "update t value before loop breaking". 
testcase is also added.