[PATCH 2 of 2] lazymanifest: don't crash when out of memory (issue5916)

[Augie Fackler]

> On Jun 13, 2018, at 10:55, Josef 'Jeff' Sipek <jeffpc at josefsipek.net> wrote:
> 
> # HG changeset patch
> # User Josef 'Jeff' Sipek <jeffpc at josefsipek.net>
> # Date 1528900880 14400
> #      Wed Jun 13 10:41:20 2018 -0400
> # Branch stable
> # Node ID d591c80025ee7316b77235b2d71c4b0f01c03123
> # Parent  cbb47a946bc0e0346bfc9f9ba505f9475de43606
> lazymanifest: don't crash when out of memory (issue5916)

queued for stable, thanks