manifest: fix possible SEGV caused by uninitialized lazymanifest fields
Before, uninitialized self->pydata would be passed to lazymanifest_dealloc()
on OOM, and Py_DECREF(self->pydata) would crash if we were unlucky.
It's still wrong to do malloc() thingy in tp_init because __init__() may be
called more than once [1], but I don't want to go a step further in stable
branch.
[1]: https://docs.python.org/2/c-api/typeobj.html#c.PyTypeObject.tp_new
"The tp_new function should ... do only as much further initialization as
is absolutely necessary. Initialization that can safely be ignored or
repeated should be placed in the tp_init handler."
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
context manager ['orig']
context manager [1, 'orig']
context manager [0, 1, 'orig']
context manager [2, 0, 1, 'orig']
context manager [2, 1, 'orig']
context manager [2, 'orig']
wrap callable object [0, 'orig']