tests/test-mq-qsave.t

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."

  $ echo "[extensions]" >> $HGRCPATH
  $ echo "mq=" >> $HGRCPATH

  $ hg init

  $ echo 'base' > base
  $ hg ci -Ambase
  adding base

  $ hg qnew -mmqbase mqbase

  $ hg qsave
  $ hg qrestore 2
  restoring status: hg patches saved state