PyBuffer_ToContiguous() has an off-by-one error when copying a buffer it thinks is non-contiguous.

To reproduce, put the following in foo.pyx and compile with Cython v0.21.2:

    cpdef foo():
        cdef unsigned char[:] v = bytearray("testing")
        print repr(memoryview(v).tobytes())

>>> import foo
>>> foo.foo()
'estingt'

(This issue was fixed for Python 3.x in issue #12834 but it was not fixed for Python 2.7.)