py3: have a bytes version of shlex.split()
shlex.split() only accepts unicodes on Python 3. After this patch we will be
using pycompat.shlexsplit(). This patch also replaces existing occurences of
shlex.split with pycompat.shlexsplit.
wrap 0: [0, 'orig']
wrap 1: [1, 0, 'orig']
wrap 2: [2, 1, 0, 'orig']
wrap 3: [3, 2, 1, 0, 'orig']
wrap 4: [4, 3, 2, 1, 0, 'orig']
wrap 0: [0, 4, 3, 2, 1, 0, 'orig']
unwrap 3: 3: [0, 4, 2, 1, 0, 'orig']
unwrap -: 0: [4, 2, 1, 0, 'orig']
unwrap 0: 0: [4, 2, 1, 'orig']
unwrap 4: 4: [2, 1, 'orig']
unwrap 0: -: ValueError
unwrap 2: 2: [1, 'orig']
unwrap 1: 1: ['orig']
unwrap -: -: IndexError