Merge #7778: [qa] Bug fixes and refactor
4444806 [qa] mininode: Combine struct.pack format strings (MarcoFalke)
faaa3c9 [qa] mininode: Catch exceptions in got_data (MarcoFalke)
fa2cea1 [qa] rpc-tests: Properly use integers, floats (MarcoFalke)
fa524d9 [qa] Use python2/3 syntax (MarcoFalke)